Cc: Arjan van de Ven <arjan@...>, Ivan Kokshaysky <ink@...>, Greg KH <greg@...>, Linus Torvalds <torvalds@...>, Greg KH <gregkh@...>, <linux-kernel@...>, Jeff Garzik <jeff@...>, <linux-pci@...>, Benjamin Herrenschmidt <benh@...>, Martin Mares <mj@...>, Tony Camuso <tcamuso@...>
I agree with Arjan about that "not a 100% overlap". It is about the
extra ext-conf-space access done while probing in drivers/pci/probe.c:
dev->cfg_size = pci_cfg_space_size(dev);
(and lspci -v will also query/show the list of extended-caps for
pci-x/pcie-x devices that have some, provided the kernel can access
ext-conf-space).
With Ivan's patch, that line would still cause one extended-conf-space
access at offset 256 for pcie/pci-x2 devices (to check the ability to
query ext-space). Arjan "opt-in" patch would prevent that extra access.
IMHO that access is OK and harmless in all cases, we are already
protected by MCFG/e820 checks, but I agree one can express a different
opinion based on trying to prevent "never-seen/potential" hardware/BIOS
bugs. FWIW it is also there that I was suggested to exclude PCI-X2
devices (when restricted to pcie, that access while probing cannot even
cause the harmless master-abort/0xffffffff), but there is a small trade-off.
Loic
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