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SubjectRe: [Bug #11550] pnp: Huge number of "io resource overlap" messages

* Bjorn Helgaas <> wrote:

> The problem seems to be that Frans has some PCI devices that are not
> configured by the BIOS, and their BARs contain zero. A PNP quirk
> checks for overlaps of PCI devices and PNP devices, and those zero-
> valued BARs of course conflict with the PNP motherboard devices that
> describe legacy hardware.
> Here's another approach based on section 3.5 of the PCI Firmware spec.
> It says:
> Since not all devices may be configured prior to the operating
> system handoff, the operating system needs to know whether a
> specific BAR register has been configured by firmware. The operating
> system makes the determination by checking the I/O Enable, and
> Memory Enable bits in the device's command register, and Expansion
> ROM BAR enable bits. If the enable bit is set, then the corresponding
> resource register has been configured.
> So instead of checking whether the BAR contains zero, the patch below
> checks the I/O, Mem, and ROM BAR enable bits to determine whether a
> BAR is enabled.

cool! Looks like a pretty significant fix, for all sorts of legacy
devices. Worth backporting?


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