Announcing coreboot 4.5

We are happy to announce the release of coreboot 4.5

The 4.5 release covers commit 80a3df260767 to commit 0bc12abc2b26.

This release is the first since the project switched from doing quarterly releases to doing biannual releases.  The next release will be in April of 2017.

Since the last release in April, the coreboot project has had 1889 commits by 119 authors.

The release tarballs and gpg signatures are available in the usual place at

There is a 4.5 tag in the git repository, and a branch will be created as needed.

Areas with significant updates:

  • Toolchain (29 commits)
    • Updated mpfr version from 3.1.3 to 3.1.4
    • Updated gcc version from 5.2.0 to 5.3.0
    • Updated binutils version from 2.25 to 2.26.1 & Fix aarch64 build problem
    • Updated gdb version from 7.9.1 to 7.11
    • Updated iasl version from 20160318 to 20160831
    • Updated python version from 3.4.3 to 3.5.1
    • Updated expat version from 2.1.0 to 2.1.1
    • Updated llvm / clang version from 3.7.1 to 3.8.0
    • Updated make version from 4.1 to 4.2.1
  • Build system (32 commits)
    • Updates for cbfstool / fmap changes
    • Order per-region files to optimize placement success
    • Add support for the ADA language and toolchain.
  • Utilities (103 commits)
    • Lint – Update, add tools  to find non-ascii & unprintable chars and to verify a single newline at the end of files
    • cbfstool – Update for Linux payloads, Honor FSP modules addresses, fix elf parsing
    • Sconfig – Add 10 bit addressing mode for i2c devices, add generic device type, support strings, pass in devicetree filename
  • General code cleanup (197 commits)
    • Cleaning up code formatting and whitespace
    • Fix spelling & capitalization
    • Removing commented out code
    • Transition away from device_t
  • TPM (55 commits)
    • Add support for Trusted Platform Module 2.0
    • SPI & refactored I2C TPM driver
  • Drivers (54 commits)
    • Add ACPI support in several drivers
    • coreboot_tables –  Extend serial port description
    • Elog – refactor, add debug info
    • I2C – add generic driver,
    • SPI – Add new chip support, major refactoring, don’t assume SPI flash boot device
  • Lib (33 commits)
    • Add real-time-clock functions
    • Add RW boot device construct
    • reg_script updates: add to bootblock, add xor support, add display support
    • Timestamp fixes & updates
  • Vendorcode
    • AMD (14 commits) – Cleanup, add libagesa.a builds, remove unused code.
    • Google (22 commits) – VBoot2 updates and cleanup
    • Intel (86 commits) – Add Intel FSP 2.0, update Broadwell DE support
  • Payloads (37 commits)
    • Subpayload support got extend and is enabled by default.
    • nvramcui: refactor, update build
    • SeaBIOS: Update stable version to 1.9.3, add bootorder file
    • iPXE: Update stable version to the last commit of July 2016
    • Fix broken linux boot sequence

Mainboard changes

Added 13 mainboards, plus a few mainboard variants not included here:

  • ADI RCC-DFF networking board (adi/rcc-dff) – intel/rangeley SoC
  • AMD Evaluation Board DB-FT3B-LC (amd/db-ft3b-lc) – amd/00730F01 (Family 16h Models 30h-3Fh (Mullins)) CPU
  • AMD f2950 / TONK 1201/2 Board (amd/f2950) – amd/geode_lx CPU
  • Apple iMAC 5.2 (apple/imac52) – intel/i945 CPU
  • Unibap Development Kit ODE E21XX – amd/00730F01 (Family 16h Models 30h-3Fh (Mullins)) CPU
  • elmex/pcm205400 – amd/Family_14 CPU
  • elmex/pcm205401 – amd/Family_14 CPU
  • Lenovo N21 chromebook (google/enguarde) – intel/baytrail SoC
  • google/gale – Qualcomm IPQ40XX SoC
  • AOpen Chromebox (google/ninja) – intel/baytrail SoC
  • google/reef – intel/apollolake SoC
  • Acer Chromebox CXI2 (google/rikku) – intel/Broadwell SoC
  • google/rotor – marvell/MVMAP2315 SoC

Removed 5 mainboards:

These were all development boards not available to the public.

  • google/bolt – intel/haswell – removed in commit 139314b
  • google/rush – nvidia/tegra132 – removed in commit e67cd9e
  • google/rush_ryu – nvidia/tegra132 – removed in commit 0c63415
  • google/slippy – intel/haswell – removed in commit bc24b85
  • intel/amenia – intel/apollolake – removed in commit c2586db

Existing boards with significant updates

  • asus/kgpe-d16 – amd/socket_G34 – Add TPM support, enable secondary serial port
  • emulation/spike-riscv: RISC-V -clean up, use generic bootblock,  look for CBFS in RAM, reimplement SBI
  • google/gru – rockchip/RK3399 SoC (76 commits) – Board bringup
  • google/oak – mediatek/mt8173 SoC- Add Elm variant, update memory, configure display, initialize touchscreen gpio
  • intel/galilleo- intel/quark SoC (14 commits) – Board bringup, add galileo gen1 support, switch to FSP2.0
  • intel/minnowmax – intel/fsp_baytrail SoC – Enable all PCIe ports, Program GPIO for power LED
  • lenovo/x60 – intel/socket_mPGA478 – init GPIOs before dock check, add hda verb table
  • siemens/mc_bdx1 – intel/fsp_broadwell_de SoC – Add external RTC, Set up MAC addresses, Update IRQs
  • siemens/mc_tcu3 – intel/fsp_baytrail SoC – cleanup & LCD panel updates

Changes in chips

Moved 3 northbridge/southbridge pairs to soc:

  • dmp/vortex86ex
  • intel/sch
  • rdc/r8610

Added 2 socs:

  • marvell/mvmap2315 (12 commits)
  • qualcomm/ipq40xx (22 commits)

Removed 1 soc:

  • nvidia/tegra132 – removed in commit 9ba0699

Added 2 sios:

  • nuvoton/nct6776
  • nuvoton/nct6791d

Existing chip areas with many changes

  • ARM (34 commits)
    • Add armv7-r configuration
    • rockchip/rk3399 (73 commits) – Bringup, memory updates
  • RISC-V (40 commits)
    • Improve and refactor trap handling
  • X86 (225 commits)
    • ACPI (40 commits) Add support for writing various entries and descriptor types, Add common definitions, Use ‘GOOG’ id for coreboot table
    • amd/mct_ddr3 northbridge: Support non-ECC DIMMs, Update SMBIOS, various fixes
    • arch/x86: many postcar stage updates, add common ACPI definitions, Support “weak” BIST and timestamp save routines
    • intel/apollolake SoC (211 commits) – Chip bringup, Update bootblock
    • intel/common: ACPI updates, Add smihandler, LPSS I2C driver, and  IGD OpRegion support
    • intel/fsp_broadwell_de: IRQ fixes, SPI message fixes, Add DMAR table to ACPI
    • intel/gm45 northbridge: Fix text mode init, enable vesa framebuffer, use VGA if connected
    • intel/i945 northbridge: add native VGA init, Update divisor calculations
    • intel/quark SoC (62 commits) – Chip bringup, add Fsp2.0 support, updates for serial console
    • intel/skylake CPU (61 commits) – Finished Skylake bringup, start updating for Kabylake FSP
    • intel/x4x northbridge (13 commits) – Memory & Graphics updates


Updated 4 submodules

  • 3rdparty/blobs (6 commits)
  • 3rdparty/arm-trusted-firmware (425 commits)
  • 3rdparty/vboot (61 commits)
  • 3rdparty/chromeec/ (676 commits)

Tested boards

The following boards were tested for this release:

  • asrock/e350m1              4.4-1890
  • asus/kfsn4-dre               4.4-1698 / 4.5-17
  • asus/kgpe-d16                4.4-1802 / 4.5-17
  • emulation/qemu-q35   4.4-1698 / 4.5-8
  • gigabyte/ga-b75m-d3v 4.4-1757
  • google/peppy                 4.4-1882
  • lenovo/g505s                 4.4-1739
  • lenovo/x201                   4.4-1886
  • lenovo/x220                   4.4-1746 / 4.5-17

coreboot statistics

Total Commits: 1889
Average Commits per day: 10.92
Total authors: 119
New authors: 47
Total Reviewers: 67
Total Submitters: 19
Total lines added: 164950
Total lines removed: -182737
Total difference: -17787

[GSoC] Multiple status registers, block protection and OTP support, wrap-up (1/2)

Hello! 🙂

GSoC 2016 coding period has come to an end and mentor’s evaluating students this week. It has been an enriching 13 weeks of reading datasheets, designing structures, coding, learning and hanging out over IRC! 😛 I’d like to take this opportunity to present my work and details on how to use it. 🙂

Firstly, to offer context to the work, here is a list of public mails and blog posts. These should give an idea as to how the discussions and work evolved. A lot of the discussions have happened over IRC, but #flashrom does not keep any logs.

The patch sets that I sent to the mailing list can be found at –

  1. Multiple status register and access protection infrastructure
  2. OTP/Security registers infrastructure
  3. Dummy chips

You can also find these over at flashrom’s patchwork. The mailing list is where the review happens (although a better alternative, IMHO, is Gerrit which coreboot uses). The patches aren’t currently merged and are under review. In any case, you are most welcome to join review (which will likely be very helpful for me). 🙂 If you’d like to look at something more on the bleeding edge, then I invite you to my GitHub.

Now, moving on how to use the work. The most exhaustive documentation on how to use it is the code itself :P, but in the following list I attempt to list scenarios –

  • For SPI chips that have multiple status registers, flashrom’s verbose output will print the status register bits and there values. Most bits are named, i.e., the datasheet refers to the bit by an abbreviation, for instance, WEL for Write Enable Latch, WIP for Work In Progress, BP for Block Protect, LB for Lock Bit and so on. The verbose output will print these names, both in abbreviated and long forms, for most chips (and these abbreviations tend to be generic across many manufacturers). However, the process for adding new chips that leverage this, and adding new bits, is a fairly easy task (I would invite you to have a look at the code 😉 for more details). The verbose output also prints the write protection mode for status register(s) in effect (software protected, hardware protected, power cycle lock down and so on).
  • In case you want to disable or enable (a particular type) write protection for status register, you can use the --wp-disable or --wp-enable[=MODE] respectively (where MODE is either of software, hardware, power cycle or permanent – you are encouraged to have a look at the man page 🙂 for more details)
  • In case you want to protect a particular range of an SPI chip from writes or erases, you will need to alter the BP, TB or SEC bits. Currently, there is a CLI that will enable you to accomplish all that. 😛 First, you’ll want to look at the list of ranges your SPI chip supports – run flashrom with --wp-list. Take note of the start address and the length of the memory range you want to protect. Then again run flashrom with --wp-set-range start=0xfff000,len=4 (0xfff000 and 4 are for representational purpose only). By now the memory range is protected, but you can additionally enable status register write protection by following what the foregoing point described.
  • For SPI chips that support OTP, you can read, write and erase OTP regions (of course for supported chips :P). For OTP operations, you have at your disposal --print-otp-status, --read-otp [,reg=], --write-otp file=[,reg=], --erase-otp [reg=] and --lock-otp [reg=]. You can read the OTP memory to a file, or you can write to the OTP region from a file, very much like reading and writing from/to SPI chip. For more details, I would again like to point you to the man page. 🙂

Since this is a work-in-progress, the CLI may change (and is very likely). Currently around 10% of SPI chips use this new infrastructure. Models of a few manufacturers (and especially exotic ones like Atmel) are yet to be fully incorporated. You are most welcome to add support for new chips or update the existing ones to support new infrastructure. 🙂

I would like to sincerely thank my mentors Stefan and David for their support and help. I am indebted to them for this opportunity and I hope that we continue to share this relationship in the future while I continue to explore and contribute to flashrom. It has been a pleasure getting to know each of them. I’d also like to thank Urja for pitching in from time to time 🙂 It was fun hanging out over IRC and helping folks asking questions there. And I am looking forward to it for years to come. 😛

In the next and final part of this post, I will highlight how we intend to improve upon this work in the future, where it will be headed and what more we have in store, so please stay tuned. 😉 Phew, this was a long one, and rightly so as it attempts to summarise a great deal of experiences. If you have any feedback, questions or comments on the blogs or code, please feel to ping me on #flashrom where I am known as hatim. You can also email me at

Thanks, and looking forward to hearing from you. 🙂 See you in the next and final part.

[GSoC] Better RISC-V support, wrap-up

In less than an hour, Google Summer of Code 2016 will be over (at least for us students). In this blog post, I will describe how you can use coreboot on RISC-V.

You can find the complete list of commits that I made during GSoC with this gerrit query.

The details

Compiling spike, the RISC-V instruction-set-level simulator

Spike, also known as riscv-isa-sim, is the reference implementation of RISC-V, and the only RISC-V platform that is currently known to work with coreboot (QEMU is nominally also supported, but the corresponding coreboot code has not been updated in a while).

First, you need to build and install libfesvr:

Then, you can compile and install spike:

  • Clone the spike git repository.
  • Apply the patch in this pull request to make console output possible.
  • Open riscv/ in a text editor and find processor_t::get_csr. Add a line that reads case CSR_MTIME: return 0;.
  • run ./configure --prefix="$HOME" --with-fesvr="$HOME" && make && make install

Compiling coreboot for RISC-V

  • Clone the coreboot git repository, if you haven’t already
  • Apply Iru Cai’s patch that updates the toolchain to GCC 6.1. You will currently have to fix a merge conflict when you apply this patch, but it’s an easy one.
  • Run make crossgcc-riscv
  • Run make menuconfig to configure coreboot. Select Emulation and SPIKE usb riscv in the Mainboard menu.
  • Run make
  • Run util/riscvtools/ build/coreboot.rom build/coreboot.elf
  • Start coreboot by running spike build/coreboot.elf. You should see a few pages of output, ending in Payload not loaded.

Compiling and running Linux

  • Clone the riscv-linux git repository and check out the priv-1.9 branch
  • Apply this patch that allows linux to be started in machine-mode.
  • Download a copy linux 4.6.x from, and unpack it. I’ll assume version 4.6.2 is used.
  • cd into linux-4.6.2/arch and symlink the arch/riscv directory from riscv-linux
  • Back in linux-4.6.2, run make O=build ARCH=riscv defconfig; cd into the newly created build directory.
  • Run make ARCH=riscv menuconfig. In the “General Setup” menu of the linux menuconfig, enter path/to/coreboot/util/crossgcc/xgcc/bin/riscv64-elf- as the cross-compiler tool prefix.
  • Run make ARCH=riscv vmlinux to compile linux.
  • Open vmlinux in a hex editor, such as hexer. Change the 8-byte number at 0x18 to 00 00 00 90 00 00 00 00; Add 00 00 00 90 00 00 00 00 to the numbers at 0x58 and 0x90, to load linux at physical addresses within RAM. It’s unfortunate that I have to recommend this step, but I did not come up with a better fix yet.

Next, you need to add vmlinux to coreboot:

  • Return to the coreboot directory.
  • Apply the remaining coreboot patches that are tagged riscv.
  • In the Payload menu, select An ELF executable payload. Instead of payload.elf, select the vmlinux file.
  • Run make and util/riscvtools/ build/coreboot.rom build/coreboot.elf again.
  • Run spike build/coreboot.elf. You should now see a Linux boot, at least partially.

Future work

Even though my GSoC is over, coreboot’s support for RISC-V can still be improved, and I intend to fix at least some of the following things:

  • As you can see above, running coreboot and linux on RISC-V currently isn’t straight-forward, but involves a few manual steps.
  • There are other RISC-V platforms that I’d like to see coreboot on, such as lowRISC.
  • Linux does not completely boot, i.e. into userspace. There are still some bugs to be ironed out.
  • Automatic testing could be used to detect regressions.
  • I only tested coreboot on RISC-V with Linux; support for other operating systems or payloads is welcome.


I’d like to thank Ron Minnich and Furquan Shaikh for being good mentors, and everyone in the coreboot community for being helpful and friendly.

[GSOC] Panic Room, Recap

Hello everyone, in the following post I’m going to recap all that I’ve managed to accomplish during the GSoC of this year.

As a disclaimer: I plan to maintain these patches until they are fit to be mainlined or rejected altogether in case of design flaws.

libpayload: replace cbfs_media api with region_device api

This patchset should be complete, I tested it quite thoroughly by using the API to update the bayou payload (separate patch). I'm still waiting on a review on this one so I suspect there will be some cause for nitpicks.
bayou: Adapt to the coreboot-v4 era

Changed the design of the payload to make it integrate better with the current infrastructure of coreboot. The majority of the changes have been documented in the appropriate wiki entry. The patchset is complete and working.
console/serialice: Add SerialICE

The patchset was started and the initial work was done by Patrick Rudolph.
I picked it up from there, fixed the problems that it had and tried to get it in shape. It currently works as expected, waiting on more review/feedback.
serialice: update QEMU to version 2.5
serialice: adapt serialice to work with QEMU stable-2.5

In its current state this patchset produces a working build, all the functionality seems to be intact and SerialICE produces the same output as with the old implementation. There could be some unforeseen problems with the changes in the QEMU infrastructure and it could use a cleanup.
[WIP] src: replace device_t type with pnp/pci_defn_t

This is one of the latest commits that I've worked on, it's still a work in progress but I plan to remove all the the improper uses of device_t and replace it with the appropriate type. It's probably gonna take a while and I suspect the patch is going to be massive. If anyone has any suggestion on how to handle this transition feel free to tell me.
tint: Fix tint and add Kconfig option

The payload works as intended. Only nit is that maintaining a separate patch to apply to the tint code is tricky/messy.
lib/selfboot: Replace rdev_mmap_full()

The code worked, even though it's been a while since I rebased the change to check for conflicts. Should be an easy fix anyway.
payloads: add support lz4 compression

selfboot: add sequential lz4 payload decompression

The functionality works as expected.
coreinfo: Add support to read timestamps

cbmem: share additional time stamps IDs

Code works as intended, the only thing missing are the commas that should split the timestamps in groups of 3 digits. I couldn't port that part since it relied on a recursive function that no longer worked.
elfwriter: Fix multi-phdrs ELFs parsing

cbfstool: Require "-m ARCH" to extract payloads and stages

cbfstool: Extract payload in ELF

One of the oldest patchset that I wrote, took a while to get it right but it seems to be working wonderfully.
region: Add writeat and eraseat support

Below are a bunch of minor patches that I’ve written to fix the bugs that I’ve encountered while working on the patches above or browsing the source tree:

i945.h: fix #include path

emulation/qemu-i440fx: add cmos.default file

nvramcui: refactor code

pc80/mc146818rtc.h: Replace leftover macro token

lenovo/x60: add GPIOs initialisation before dock check

serialice: update lint filters

payloads: add Kconfig option for bayou

libpayload: split "Drivers" config section in Kconfig

bayou: delete pbuilder utility

filo: Specify libpayload path

cbfstool: Allow to easily build the individual tools

If you have any question regarding these patches you can find me on IRC (avengerf12).

I wanna conclude this post by expressing my gratitude towards the coreboot’s GSoC admins and mentors for the wonderful opportunity that they have given me and to the coreboot community for all the help and suggestions.



[GSOC] Panic Room, week #8,*

What have you worked on during the past few weeks?

I tried to finish one of the optional goals of my proposal:

a way to access a payload (possibly a recovery) after the hardware initialisation is complete but the OS has still not taken over.

To define it in more practical terms, I wanted to replace the running payload at the press of a predefined button.

I started by looking into the SMM (System Management Mode) and in particular the SMI (System Management Interrupts) handlers defined by each target board in the coreboot tree.

That was the easy part, it took just a bit of probing my board (Lenovo x60) and a serial cable to retrieve some of the SMI button codes (I planned on using the ThinkAdvantage button, code 0x19).
I added it to the appropriate smihandler.c file, defined the behaviour and that was about it.

The more difficult part was actually implementing a way to make it possible to boot a new payload while in SMM.
SMM can be considered a separate “module” from romstage, etc, this consequently means that it does not have access to all of the same functions.
In particular it cannot access the load_payload() and run_payload() functions defined inside prog_loaders.c, which, as the name implies, are necessary in order to use a payload.

In order to solve the problem I came up with two designs:

  • The first design is quite simple, but in my opinion a bit messy.
    It involves including all of the missing source files into the SMM module at compile time, a.k.a adding more entries inside the scattered around the source tree.
    I went down this route for a while until I stumbled on a function that needed to use a malloc(), this was expected so I included the definition of that function.
    It then asked to have access to the heap (_eheap) in order to allocate the memory requested, the problem is that the heap is not defined inside SMM.
    I grepped through the source code and found very little about what I was supposed to do in order to define it, so I had to let it go.
    (To add a little bit of context, this was yesterday and if you take a look at this post’s date you’ll realise that there is only 1 day left of GSoC, panic!)
  • The second approach consists of leaving SMM mostly as it is now, and instead find a way to communicate with ramstage, in order to boot the desired payload.
    The thought process was that, if cannot call a function directly from SMM, I would have to use the functions already in place in ramstage, unfortunately those functions are called only once, after the initialisation is done.
    This is where the CMOS memory comes in, I modified the payload loading process and instead of using an hard-coded path defined at compile-time, I made it check for a string inside CMOS and use that as the payload path.
    This method, however, also presented some problems:
    – It seems that currently cmos.defaults is completely ignored and the CMOS string values are not initialised as intended (at least on my board), therefore the payload path resulted always blank.
    – There needs to be quite a bite of space in the CMOS to keep the path there.
    The usual path (fallback/payload), occupies around 160 contiguous bits of the 1024 available ones, which also need to share space with other important configuration bits such as RTC, etc.
    In order to circumvent these limitations it would be possible to replace the string path in the CMOS with an enumeration of the possible paths, this however would need to be defined, maintained and shared both in the CMOS and the rest of coreboot.
    However, same as above, I ran out of time.

That about sums it up for the past few weeks.

Thank you for reading and have a nice week.

Rewriting history (of flashrom)

Sorry to interrupt the stream of GSoC posts! 😉 Some of you may have wondered why there were no flashrom commits at all since the 0.9.9 release in March (i.e. about 5 Months). There wasn’t much direct flashrom development going on on the vanilla branch of flashrom apart from Hatim’s GSoC efforts of course.

Instead I’ve been working on moving our repository to git. I have created some client- and server-side hooks + other infrastructure (with the help of Patrick) that will be used in the future to host the vanilla flashrom repository. This part was actually only the smaller part of time I spent on flashrom in the last months (which was not as much as I would have wished for, obviously). More on this and future development later on the flashrom mailing list…

The remaining time I’ve been working on a script that rewrites history. Not all of history, only the flashrom repository’s history. Continue reading Rewriting history (of flashrom)

[GSoC] Better RISC-V Support, week #10

This past week, I worked on the virtual memory initialization code of coreboot on RISC-V. The first part of this was to update encoding.h a file that defines constants such as bit masks which are necessary for interacting with RISC-V’s Control and Status Registers. As a result, I also had to change a few files that relied on outdated constants. Then I wrote some code to walk the page table structures, and fixed one or two bugs in the page table setup code. Unfortunately my patches aren’t as finished as I would like them to be.

When I tested my changes with a Linux payload (which I had to edit the ELF headers of, because Linux uses virtual addresses, while cbfstool and the SELF loader use physical addresses), I stumbled upon another strange error: I get a store access fault in the instruction of the trap handler that saves the first register, even if I initialize the stack pointer to a value that’s within the RAM. When the trap handler runs again to handle this store access fault, it runs without any problems. This fault is especially confusing, because machine mode should always be able to access RAM through its physical addresses.

What’s next?

During the next week, I’ll be traveling and won’t be able to work on coreboot. When I return, I will rework my patches so they can be merged, and hopefully understand the aforementioned access fault problem. Properly set-up page tables should bring me a step closer to running Linux on coreboot/RISC-V (without bbl in the middle).

If time permits, I will start porting coreboot to the Nexys 4 DDR devboard.

[GSOC] Panic Room, week #7

What have you procrastinated on this past week?

As usual, I’m glad you asked.

During the past week I worked every day(/night) on the porting of the region_device API (commit) as I probably mentioned last week. The port is now complete and it should be bug-free (?).
It’s been tested pretty thoroughly since I immediately used it to adapt Bayou from the old LAR/coreboot-v3 paradigm to the new CBFS/coreboot-v4 one.
A bunch of bugs cropped up with the new API during the transition (debugging the API wasn’t fun at all) but they have been solved and unless for some corner-cases that I missed it should just work.

The second part of the week, as you might have guessed read, has been devoted to fixing Bayou (commit). This has been quite fun, almost everything was broken or relied on some old function that has since been dropped from libpayload.
It now works quite well and supports all of the original features.
The only problem now are with the other payloads since they aren’t all able to exit cleanly and give back control to bayou (i.e. coreinfo reboots before returning, tint halts, etc).
If you want to know more details take a look at the commit message.

Apart from this two items I wrote a couple of patches concerned with libpayload and a patch that adds support for sequential lz4 decompression during the boot process (Thank you, Julius Werner, for pointing that out).
I also just finished updating the wiki entry for Bayou, so if someone wants to test it out… 🙂

What’s next?

With less than a month left of my GSOC time I plan to dedicate solely to maintain the patches that I currently have and work on the coreboot/serialice integration (so as to finally do something pertinent to the original proposal).

Have a nice weekend!



I had to drop the idea of working on the FILO (flashupdate) project since it relies on a series of patches that have not been finished yet (libflashrom). It will be a project for another time perhaps.


I think I lost count of a few weeks here and there…

[GSoC] Multiple status registers, block protection and OTP support, week #6, 7, 8 and 9

Hello! I have been away for some time now, so this is going to be a longer post. I hope you have missed hearing from me 😛 In this post I will talk about my work in the weeks post-midterm evaluations. After a discussion with my mentors in the midterm evaluations week, we decided to shift focus towards the first three phases of my GSoC proposal for the remainder of the duration. Work on the final phase will be done after GSoC along with the more long-term goals that have come up as I have been making progress.

I submitted patches (finally ;)) to the mailing list. The set of patches adds multiple status register, and block protection infrastructure. I have also added a command-line interface to expose the new functionality. Although I am not sure that the exact wording of the CLI is most optimum, but I did not spend a lot of time on that because IMO it is a rather subjective issue and altering it is not a difficult task. The set of patches also adds support for new infrastructure to around 90 existing chips. I am still waiting to receive feedback and review on them. (My mentors had been slightly busier then.) I am also investigating adding support for access protection to non-SPI chips. This isn’t on the highest priority (more like a long-term goal), but once the SPI infrastructure gets merged, I will begin writing code for that.

Based on the initial prototypes I built (here, here and here), we had decided to use pointers to new structs instead of fully embedding them in struct flashchip. This decision really started to show when I was adding support for existing chips – with only 25 unique struct definitions we were able to support those 90 chips! 😉 One of the problems I faced was that I needed to test the new infrastructure, but doing so on a physical chip would be cumbersome. So that problem was solved by adding a dummy chip to use with flashrom’s dummy programmer. (At that time the code was the dummy chip was messy and something I would be ashamed to put up publicly, but now I have improved upon it! :P)

Currently I am working on finalising the OTP/security register(s) patches – more specifically, adding support to existing chips, code cleanup and documentation. I will be able to send them to the mailing list in a few days. In my research on Eon, GigaDevice and Winbond chips, 2 distinct models for OTP were observed – the GigaDevice and Winbond model with security register(s), and the Eon model with a security sector.

The Security Register(s) model has 3 separate opcodes for read, program and erase – 0x48, 0x42 and 0x44 respectively. A chips can have multiple security registers (most commonly 3, but as high as 4) with each register being anywhere between 128 bytes to 1024 bytes in size (most commonly 512 bytes and then 256 bytes). Usually chips have a lock bit (LB1, LB2, …) in the status register that correspond to respective security registers. These one-time programmable bits are changed using the standard WRSR instruction. Some chips have a single lock bit that controls OTP status for all security registers.

The Security Sector model has a separate sector which can be operated in the OTP mode. OTP mode is entered with opcode 0x3A and exited by sending WRDI (0x04) instruction. While in the OTP mode, the sector behaves just like any other sector – normal read, program and erase instructions apply. The SRP/SRWD bit is served as OTP bit while in OTP mode. Issuing the WRSR command (irrespective of the data sent along with it) will cause the one-time programmable OTP bit to be set.

One of the recurrent issues (for the lack of a better word, I don’t think of it to be an issue really ;)) is that many chips I have based my research on, are not originally supported by flashrom (perhaps unfortunate siblings of the same family that didn’t find support in flashrom earlier xD). I don’t call it an issue per se because after I have submitted my patches flashrom will end up supporting even more chips, but since I have to write more code it might take slightly longer to submit the patches.

There is a third model which is dominantly followed by Spansion chips and a couple of AMIC chips (some AMIC chips follow one of the earlier models – it’s like AMIC couldn’t decide which one to stick to or they probably had different teams working on it! :P). Similar to the security sector design, these chips also have a separate OTP sector but instead of storing configuration in the register, a byte within the sector is allocated for storing the configuration data. I have planned to support this model in the next revision of patches, after the upcoming ones get reviewed and merged.

Thanks for your time, it was nice to get back in touch with you! 🙂
(Phew, that was long! :P)

[GSoC] Better RISC-V support, week #6/7/8/9

Since I haven’t posted an update of my coreboot-on-RISC-V work in a while, this will be a slightly longer post.

Week 6

In week 6, I started documenting how to build and boot coreboot on RISC-V, in the coreboot wiki.
It is now a bit outdated, because we’re moving away from using bbl to boot Linux.

Week 7

I wrote some patches: I removed code that used the old Host-Target Interface (HTIF), because it’s deprecated. I submitted an improved version of my workaround for the bug that causes Spike to only execute 5000 instructions in some cases. I informed the coreboot resource management subsystem about the position of the RAM in physical address space, so that the program loader wouldn’t refuse to load segments into RAM. I submitted two patches to fix compiler errors with the new toolchain.

Meanwhile, there were some good news in the RISC-V world:

Week 8

I submitted a few more patches and started to explore the Nexys4 board. The precompiled bitstream and kernel from the lowRISC version 0.3 tutorial worked without any problems, and after a few days and some help from the lowRISC mailing list, I was able to recompile the lowRISC bitstream.

This week

I discussed the choice of boot medium with the lowRISC developers, and they agreed that a memory-mapped flash would be useful. Once it is implemented, I
can start porting coreboot to lowRISC on the Nexys 4 DDR board. Luckily the Nexys4 already has large enough flash to use for this purpose.

My mentors and I agreed that the switch from machine mode to supervisor mode should be left completely to the payload.

What’s next?

I will continue to work on running coreboot on the Spike emulator. Currently I’m facing the following problems and tasks:

  • Linux, when compiled to an ELF file (vmlinux) specifies that it wants to be loaded at the physical address 0x0 and at the virtual address 0xffffffff80000000. Since coreboot’s ELF loading code only looks at the physical address, it refuses to load Linux, since RAM starts at 0x80000000 on RISC-V.
  • Low level platform information (most importantly the memory layout) is passed to the firmware (coreboot in this case) as a configuration string, which is dynamically generated by the emulator, in the case of Spike. I still need to implemented a parser for this format, so coreboot can know how much memory is available.
  • The RISC-V Privileged Architecture Specification 1.9 specifies that there shall be a page at the top of the virtual address space where the operating system can call a few functions exposed by the firmware (this is the Supervisor Binary Interface).