Bjorn Helgaas schrieb:
On Wed, Jan 18, 2012 at 8:49 AM, Martin Burnicki
<martin.burnicki@xxxxxxxxxxx> wrote:
Hi folks,
I'm maintaining the driver software for the PCI cards manufactured by our
company, Meinberg Funkuhren in Germany. Basically our Linux driver supports
all our PCI cards on all Linux kernels 2.6.x and 3.x. The PCI cards are e.g.
GPS receivers, radio clocks, or IRIG time code receivers.
Recently I've run into a problem with our PCI Express cards in a certain
server PC: There are 8 PCI Express slots on the mainboard, and in some of
the slots the cards work properly, but in some other slots on the same
machine they don't work since the cards are not accessible by the kernel
driver.
In cases where the cards are not accessible lspci -v reports
for the I/O base address 0:
Region 0: I/O ports at<ignored>
From the lspci source (http://mj.ucw.cz/sw/pciutils/), it looks like
this happens when the BAR contains zero.
This must be the BAR value saved inside the kernel's device structure.
The confguration space dump of lspci -x shows that even in this case a
usual I/O address has been assigned to BAR0 on the card.
Finally I tried different Linux distributions with different kernel versions
and found that the same card in the same slot with the same driver works
properly under kernel 2.6.32 and earlier, but doesn't work anymore under
kernel 2.6.36 and later, including kernel 3.1.4. So there must have been
some code changes in the newer kernel versions which prevent the card from
being accessed via I/O, and let lspci say "I/O ports at<ignored>".
Please open a bug report at http://bugzilla.kernel.org, category
Drivers/PCI, mark it as a regression, add me to the CC: list, and
attach complete dmesg logs from 2.6.32 and 3.1.4 with the card in the
slot that no longer works.
Done:
https://bugzilla.kernel.org/show_bug.cgi?id=42606
Thanks again!
Martin
--
Martin Burnicki
Meinberg Funkuhren
Bad Pyrmont
Germany
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