Hello Matt, On 04.06.19 22:21, Matt B wrote:
Pretty much all AMD GPUs (both integrated and otherwise, including PCIe cards) rely on vgabios blobs for init and to support the driver(s) > From what I've heard, the people writing open source drivers for these GPUs really don't want to deal with the init and modesetting, ect. Does this mean it's more practical to try to make open source versions than to try to eliminate their use outright?
the display engine (modesetting and such) seems to be undocumented for AMD devices. I guess many people would actually be happy to write proper open-source code for it (including myself). But without documentation from AMD it is a PITA.
If that's the case, it seems like there's insufficient tooling?
No, AFAIK it's just insufficient documentation. While AMD documents the computational/3D engine part of their hardware, the display engines are undocumented (unless that changed for recent generations). It's quite odd, I've never heard about any silicon vendor that is closed up as AMD on the matter. I guess it's some internal political issue because sb. is convinced that AtomBIOS (their closed implementation) is the way to go. Maybe we have to wait until the stakeholders retire.
There's been some stuff about reading and writing of vgabios blobs with flashrom [1]
This is just about being able to write to the flash chip on a graphics card.
but I haven't heard anything about a compiler or toolchain that can produce them. The closest is the available disassembler [2], which can provide some insight but probably wouldn't be useful for building vgabios blobs from source as part of a coreboot build. (I think there were also some modified radeon drivers for tracing vgabios calls, but I can't find them now)
I don't see the incentive behind creating some "open-source" version that simply replicates what the original VGABIOS does, without anybody understanding what it does. If you were happy with that, couldn't you just use the original binary? Nico
[1] https://www.phoronix.com/scan.php?page=news_item&px=Flashrom-AMD-SPI-Patches [2] https://www.phoronix.com/scan.php?page=article&item=amd_atombios_dumper&num=1
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