On 11/12/2018 11:02 PM, Bjorn Helgaas wrote: > > [EXTERNAL EMAIL] > Please report any suspicious attachments, links, or requests for sensitive information. > > > [+cc Jon, for related VMD firmware-first error enable issue] > > On Mon, Nov 12, 2018 at 08:05:41PM +0000, Alex_Gagniuc@xxxxxxxxxxxx wrote: >> On 11/11/2018 11:50 PM, Oliver O'Halloran wrote: >>> On Thu, 2018-11-08 at 23:06 +0000, Alex_Gagniuc@xxxxxxxxxxxx wrote: > >>>> But it's not the firmware that crashes. It's linux as a result of a >>>> fatal error message from the firmware. And we can't fix that because FFS >>>> handling requires that the system reboots [1]. >>> >>> Do we know the exact circumsances that result in firmware requesting a >>> reboot? If it happen on any PCIe error I don't see what we can do to >>> prevent that beyond masking UEs entirely (are we even allowed to do >>> that on FFS systems?). >> >> Pull a drive out at an angle, push two drives in at the same time, pull >> out a drive really slow. If an error is even reported to the OS depends >> on PD state, and proprietary mechanisms and logic in the HW and FW. OS >> is not supposed to mask errors (touch AER bits) on FFS. > > PD? Presence Detect > Do you think Linux observes the rule about not touching AER bits on > FFS? I'm not sure it does. I'm not even sure what section of the > spec is relevant. I haven't found any place where linux breaks this rule. I'm very confident that, unless otherwise instructed, we follow this rule. > The whole issue of firmware-first, the mechanism by which firmware > gets control, the System Error enables in Root Port Root Control > registers, etc., is very murky to me. Jon has a sort of similar issue > with VMD where he needs to leave System Errors enabled instead of > disabling them as we currently do. Well, OS gets control via _OSC method, and based on that it should touch/not touch the AER bits. The bits that get set/cleared come from _HPX method, and there's a more about the FFS described in ACPI spec. It seems that if platform, wants to enable VMD, it should pass the correct bits via _HPX. I'm curious to know in what new twisted way FFS doesn't work as intended. Alex > Bjorn > > [1] https://lore.kernel.org/linux-pci/20181029210651.GB13681@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx >
