On Thu, Nov 3, 2011 at 3:16 AM, Thomas Renninger <trenn@xxxxxxx> wrote: > On Monday, October 31, 2011 04:51:07 PM Bjorn Helgaas wrote: >> On Mon, Oct 31, 2011 at 4:33 AM, Thomas Renninger <trenn@xxxxxxx> wrote: > >> Seems like these are BIOS bugs. Do we know for sure that Windows >> consumes this information that seems to be wrong? Have you had a >> conversation with the vendor about whether the BIOS is at fault here? > Such closed specifications between a major OS and specific HW vendors > should be forbidden by law and I expect in some countries you'll win > if you contest this contract in a high enough court... > APEI is based on the Windows WHEA specification which only specific > vendors can retrieve from Windows if they sign an NDA contract. > I could imagine there you find details about the GAS structure usage > in WHEA/APEI tables the way Windows like it. > > After looking at quite a lot APEI tables and their bit width, byte access > and mask values, I am pretty sure bit width is ignored on Windows. > Or say, if these tables are used, access width is always correct while > bit width is not. > >> If we make Linux ignore the bit_width, that might "fix" these boxes >> with broken BIOSes, but at the cost of breaking a box that uses >> bit_width correctly. > None of the "broken bit width" boxes I looked at should break if > access width is used. Yes, but bit_width is a standard part of the ACPI generic address structure, and there's nothing to prevent a future BIOS from using it and expecting it to work as documented. If we make Linux ignore/override the bit_width now, we'll build a legacy of machines that depend on the fact that we ignore it, and then we would have no way to deal with future machines that might expect us to pay attention to it. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
