It turns out that some UEFI systems provide apparently an apparently valid PCI ROM BAR that turns out to contain garbage, so the attempt in547b52463to prefer the ROM from the BAR actually breaks a different set of machines. As Linus pointed out, the graphics drivers are probably in the best position to make this judgement, so this basically reverts547b52463andf9a37be0fand adds a new helper function. Followup patches will add support to nouveau and radeon for probing this ROM source if they can't find a ROM from some other source. [bhelgaas: added reporter and bugzilla pointers, s/f4eb5ff05/547b52463] Reference: https://bugzilla.redhat.com/show_bug.cgi?id=927451 Reference: http://lkml.kernel.org/r/kg69ef$vdb$1@ger.gmane.org Reported-by: Mantas Mikulėnas <grawity@gmail.com> Reported-by: Chris Murphy <bugzilla@colorremedies.com> Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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