[bug #47101] reopening of "simple network" protocol in efinet causes thinkpad crash

[chrysn]

URL:
  <http://savannah.gnu.org/bugs/?47101>

                 Summary: reopening of "simple network" protocol in efinet
causes thinkpad crash
                 Project: GNU GRUB
            Submitted by: chrysn
            Submitted on: Tue 09 Feb 2016 04:45:05 PM GMT
                Category: Network
                Severity: Major
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: Git master
         Reproducibility: Every Time
         Planned Release: None

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Details:

when serving grub via pxe to thinkpad configuerd to uefi (x86_64-efi), in
particular a thinkpad edge e135 with bios version HMET90WW (2.50) and machine
type model 335963G), the system immediately reboots when it hits the
grub_efi_open_protocol in drivers/efi/efinet.c's open_card function, right
where it says "Try to reopen SNP exlusively to close any active MNP protocol
instance that may compete for packet polling" in the comment.

replacing the line with `net = NULL;` in the current master (67dba97e4),
things work fine -- the rest of the setup runs smoothly into boot just like it
does when the same hardware is set to boot via bios.

now the exclusive protocol reopening looks basically justified in the sense
that "just drop the mechanism" is probably not the right solution, but "if you
encounter this behavior, try rebuilding grub with said line commented out" or
"always use the latest bios version" is probably not either.

what are other options? can the reloading-feature be probed before running it
and risking the reboot? can the uefi bios version be queried and the
exclusive-reopen bypassed if the version is known to be bad?




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