Hello.
I tried seabios on an emulator (not qemu) and faced the PCI memory regions overlap. After some debugging I came to the conclusion that seabios simply forgets to align the base addresses, and as the result, when the device aligns the address down by clearing the "dont care" bits, it can overlap the previous region. I fixed the problem with the attached simple patch. Still it is hard to believe such a bug can exist, so I wonder if I am missing something. Any suggestions to where should I dig to narrow the problem further? Or can it be that seabios actually has the bug like that and no one have noticed? :)
On Do, 2017-04-20 at 01:18 +0300, Stas Sergeev wrote:
Hello.
I tried seabios on an emulator (not qemu) and faced the PCI memory regions overlap. After some debugging I came to the conclusion that seabios simply forgets to align the base addresses, and as the result, when the device aligns the address down by clearing the "dont care" bits, it can overlap the previous region. I fixed the problem with the attached simple patch. Still it is hard to believe such a bug can exist, so I wonder if I am missing something. Any suggestions to where should I dig to narrow the problem further? Or can it be that seabios actually has the bug like that and no one have noticed? :)
The problem must be somewhere else. seabios orders the pci bars by size, for best packing, and that should also get the alignment right. You shouldn't see unaligned bars at the place where you patch the code.
Any chance you've patched seabios to support your emulator?
cheers, Gerd
21.04.2017 09:59, Gerd Hoffmann пишет:
On Do, 2017-04-20 at 01:18 +0300, Stas Sergeev wrote:
Hello.
I tried seabios on an emulator (not qemu) and faced the PCI memory regions overlap. After some debugging I came to the conclusion that seabios simply forgets to align the base addresses, and as the result, when the device aligns the address down by clearing the "dont care" bits, it can overlap the previous region. I fixed the problem with the attached simple patch. Still it is hard to believe such a bug can exist, so I wonder if I am missing something. Any suggestions to where should I dig to narrow the problem further? Or can it be that seabios actually has the bug like that and no one have noticed? :)
The problem must be somewhere else. seabios orders the pci bars by size, for best packing, and that should also get the alignment right. You shouldn't see unaligned bars at the place where you patch the code.
Thanks, I'll check that in a week. What I know to the date, is that the large memory region was overlapping with the small ROM region. So they were of a different type, and maybe this is why sorting didn't work. I'll try to check.
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Gerd Hoffmann -
Stas Sergeev