Hi Alex,
On 20.02.19 15:56, Alex Feinman wrote:
I think I almost got to the bottom of it. I thought, incorrectly, that the VBT on my system is not accessible because I trusted intelvbttool from utils/ to dump it.
ah, quite some misunderstanding. You said initially the "VBT cannot be located" and I automatically assumed your OS driver doesn't pick it up.
It is outdated as it relies on VGA option ROM.
It's not a perfect tool, but doesn't lack anything obvious. I mean a switch like `--inoprom` of course relies on an option ROM, and `--inlegacy` not working with UEFI shouldn't surprise either.
If I use the intel_vbt_decode from intel-gpu-tools package (Ubuntu), I can see the VBT just fine: sudo intel_vbt_decode --file /sys/kernel/debug/dri/0/i915_vbt
That file lies in a virtual file system which reports a size of 0, that's where intelvbttool fails. But it works generally:
# cp /sys/kernel/debug/dri/0/i915_vbt /tmp/ # intelvbttool --invbt /tmp/i915_vbt --outdump
Should show a dump (not a very comprehensive one).
As for VBT - the way to set it up is to use vbt.bin (renamed to vbt.dat) and vbt.bsf with intel BMP.exe or bct tool supplied in the FSP GIT.
Yes, that's the only known option to edit a VBT (beside a hex editor).
I think it would be nice to document that intelvbttool does not work in UEFI/GOP setups (and is generally speaking obsoleted by the new utilities in the intel-gpu-tools package).
It doesn't seem that black and white. The dump mode of `intelvbttool` could be dropped, I guess (I never really used it). That would make it more obvious that it's more useful for file mangling. Patches are welcome.
About documentation, it would be really nice if you could write some- thing up [1]. Even if it's just one paragraph for each tool (and a reference to BMP). I guess the most precious information is the path `/sys/kernel/debug/dri/0/i915_vbt` ;) might be worth to patch that into the help text of intelvbttool (along with support to read it directly).
Nico
[1] We maintain documentation in the coreboot repository below `Documentation/`. https://doc.coreboot.org/getting_started/writing_documentation.html The only other page about graphics seems to be: https://doc.coreboot.org/gfx/libgfxinit.html Might be worth to group that somehow (reminds me, that page needs an update).