On Thu, Nov 7, 2019 at 12:02 PM Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> wrote:
Hi,The OS and BIOS both assumed behavior as before eed85ff4c0da7 -- AER
On 10/25/19 1:20 PM, Bjorn Helgaas wrote:
On Wed, Oct 23, 2019 at 12:22:05PM -0700, Olof Johansson wrote:I need some clarification on this issue. Do you mean in these systems,
In commit eed85ff4c0da7 ("PCI/DPC: Enable DPC only if AER is available"),Some systems do not grant OS control of AER via _OSC. I guess the
the behavior was changed such that native (kernel) handling of DPC
got tied to whether the kernel also handled AER. While this is what
the standard recommends, there are BIOSes out there that lack the DPC
handling since it was never required in the past.
problem is that on those systems, the OS DPC driver used to work, but
after eed85ff4c0da7, it does not. Right?
firmware expects OS to handle DPC and AER, but it does not let OS know
about it via _OSC ?
handled by firmware but DPC handled by kernel.
I.e. a classic case of "Sure, the spec says this, but in reality
implementations relied on actual behavior", and someone had a
regression and need a way to restore previous behavior.
--
-Olof