[coreboot] Support for Gigabyte ga-ma78gm-us2h?

Mike Banon mikebdp2 at gmail.com
Sun Oct 2 17:18:01 CEST 2016

First of all, I recommend that you get a hardware programmer for BIOS
chips (e.g. cheap CH341A) together with DIP8 test clip (if your type
of BIOS chip is indeed DIP8 according to Supported Motherboards wiki
page) to do In-System Programming with a flashrom. Thanks to a test
clip you will not need to solder your board in order to flash a BIOS.
Backup a current BIOS image from your AM1ML board, then replace it
with coreboot rom, and if it doesn't work - you could restore your
original BIOS to make your board boot again and submit some bug
reports and/or investigate personally (e.g. using POST card, serial
console, etc.)

About GA-MA78GM-US2H IOMMU support:

1) Official BIOS:

Sadly it seems to be unknown whether official BIOS supports IOMMU,
tried searching it online and everyone whom I found seems to be
running it with IOMMU disabled ("Please enable the IOMMU option in the
BIOS setup" in kernel log). Maybe it doesn't have

2) Coreboot:

Probably the easiest way of determining what coreboot boards have
iommu support is running these commands:

cd ./coreboot/
find . -type f -print0 | xargs -0 grep "iommu"
find . -type f -name "cmos.layout" -print0 | xargs -0 grep "iommu"

For example, could see " /src/mainboard/biostar/am1ml/ " there. By not
seeing " /src/mainboard/gigabyte/ma78gm/ " , "
/src/southbridge/amd/rs780/ " and " /src/southbridge/amd/sb700/ " I
think that this board does not have IOMMU support currently. However,
when running " find . -type f -print0 | xargs -0 grep "iommu" " after
building a coreboot for GA-MA78GM-US2H :

Binary file ./build/coreboot.rom matches
Binary file ./build/cbfs/fallback/romstage.elf matches
Binary file ./build/cbfs/fallback/romstage.debug matches
Binary file ./build/cbfs/fallback/ramstage.debug matches
Binary file ./build/generated/ramstage.o matches
Binary file ./build/ramstage/arch/x86/acpi.o matches
Binary file ./build/romstage/mainboard/gigabyte/ma78gm/romstage.o совпадает
Binary file ./build/coreboot.pre matches

Strangely, a few mentions of IOMMU inside the compiled files could be
found with okteta hex editor. In addition, I am not sure if this SB700
/ RS780 supports IOMMU on hardware level. Could please someone clarify

If you are looking for other AMD boards supported by coreboot which
have a guaranteed support of IOMMU, you could run a command above
(almost all results are AMD). Just don't forget to check Supported
Motherboards wiki page to see their current status, many of them are
red (unknown if they work, since no one submitted a coreboot report
for them). I personally tested that my Lenovo G505S AMD board supports
IOMMU, but this is a laptop so you might be not interested if you want
to use desktop graphic cards

BTW please submit a board status report if you will successfully boot
a coreboot on your Biostar AM1ML. Currently it has a yellow status,
last report is one year ago...

On 10/02/2016 01:15 AM, Taiidan wrote:
> I am curious, does the default bios properly support IOMMU with graphics forwarding?
> And does coreboot support that as well? the wiki page doesn't say
> What blobs do you need to make it work?
> I am looking to purchase a new coreboot compatible motherboard and that is a must have, although if CB doesn't work out I still want a working motherboard.
> I hope you are able to figure it out.
> On 09/25/2016 11:07 AM, Alberto Simón Francés wrote:
> > Hello,
> >
> > I've been trying to make this board boot and I haven't had much success.
> > Sometimes I've been able to get it to POST, but it's not something that
> > happens consistently. Since I can't find much info other than it being
> > listed, I'm asking here to see if by any chance there's something that I'm
> > missing, because I feel like I'm just trying random things to see what
> > sticks.
> >
> > Thankfully the board has dual bios, so it's easy to go back if I mess
> > something up. Please, help.
> >
> > Best regards,
> > Albert
> >
> >

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