[Linux-kernel-mentees] [RFC PATCH 00/17] Drop uses of pci_read_config_*() return value
helgaas at kernel.org
Sun Aug 2 19:14:06 UTC 2020
On Sun, Aug 02, 2020 at 08:46:48PM +0200, Borislav Petkov wrote:
> On Sun, Aug 02, 2020 at 07:28:00PM +0200, Saheed Bolarinwa wrote:
> > Because the value ~0 has a meaning to some drivers and only
> No, ~0 means that the PCI read failed. For *every* PCI device I know.
Wait, I'm not convinced yet. I know that if a PCI read fails, you
normally get ~0 data because the host bridge fabricates it to complete
the CPU load.
But what guarantees that a PCI config register cannot contain ~0?
If there's something about that in the spec I'd love to know where it
is because it would simplify a lot of things.
I don't think we should merge any of these patches as-is. If we *do*
want to go this direction, we at least need some kind of macro or
function that tests for ~0 so we have a clue about what's happening
and can grep for it.
More information about the Linux-kernel-mentees