Re: Possible issue with dangling PCI BARs

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> So disabling memory or IO decode in a command register seems to be
> the only safe option. This depends on architecture, though.

You are assuming a degree of sanity that seems unwise (at least for PC
class hardware).

Whether a given BAR is decoded depends not only on the contents of the
BAR but also the hardware configuration *specific* to the device.

The SIL680 for example has an MMIO BAR at BAR5. Control for that BAR is
via MMIO_EN which is a bit in PCI config register 0x8A.

So if we disable the device because of a dangling BAR the users root file
system goes away. If we leave it as is we have to know the
firmware/hardware came up with that BAR disabled or how to control it at
a per device level.

Supporting pci_enable_device_io / pci_enable_device_mmio / pci_iomap_io /
pci_iomap_mmio seems to cover pretty much all the use cases we have. 

The users we have right now that are:

	- pata_cs5520   (can be dealt with easily)
	- old IDE	(with the new resource handling for legacy IDE
can use pci_enable_device_io I think, ditto pci/cs5520)
	- scx200_acb	(looks like a simple substitution works)
	- lpfc		pci_enable_device_mmio
	- qla2xxx	pci_enable_device ? (enables IO and MMIO)

Alan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/