On Thu, Mar 18, 2010 at 03:31:55PM -0400, Don Dutile wrote:
> Matthew Wilcox wrote:
> > So we need to figure out why your machine doesn't support extended
> > config space. What chipset does it use? Is there a BIOS update available
> > for it? What does it report in dmesg for config space accesses?
>
> In addition to having MMCONFIG enabled on the system (hw & kernel),
> you also need to be root because of this snippet in drivers/pci/pci-sysfs.c,
> pci_read_config():
> unsigned int size = 64;
> loff_t init_off = off;
> u8 *data = (u8*) buf;
>
> /* Several chips lock up trying to read undefined config space */
> if (capable(CAP_SYS_ADMIN)) {
> size = dev->cfg_size;
> } else if (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS) {
> size = 128;
> }
>
> which will truncate the read to 1st 64-bytes, so unpriv user can't
> crash a system that has badly behaving PCI(e) config space.
>
> IMO, the CAP_SYS_ADMIN ought to be replaced w/a quirk check
> for badly-behaving devices &/or chip sets.
Joyce already said at the start of the thread that they were able to
get 256 bytes of config space. Please don't hijack this thread where
a user is receiving help.
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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