Red Hat Bugzilla – Bug 245048
PCI Express devices behind a PCI-Express to PCI bridge are not reassigned to new IRQ's by the OS.
Last modified: 2015-01-04 17:29:50 EST
Description of problem: Communication devices behind a PCI-Express to PCI
bridge are not assigned new IRQ's by Fedora Core 7. You can see in the
attached BIOS log that the BIOS assigned 2 Simple COMM. Cntrlr devices to IRQ
10. These should have been reassigned 2 new separate IRQ's by the OS. If you
review the attached dmesg and messages file, the devices are left on IRQ 10.
The IO addresses of the 2 boards can be read in the LSPCI log. If you review
the messages file, those IO ranges are assigned IRQ's only to the PCI bus. Our
PCI-Express multi-port serial boards do not work as a result. We can get one
board to work by itself if we add only 1 board, and use the 'noapic' boot
option in the grub.conf file. I am not sure if this is a problem with the OS
PCI assignment, or an issue with pciutils. This problem does not happen in
Windows XP/Server 2003, etc. We don't have any problems with the PCI-X,PCI
version of the same board.
Version-Release number of selected component (if applicable): PCIUTILS version
2.2.5 (dated 5/4/07)
Fedora 7.0.1 (dated 5/31/07)
Motherboard: Gigabyte GA-965G-DS3
Bios: 965G-DS3 Version F9 (dated 5/28/07)
How reproducible: 100% reproducable. None of our PCI-Express Multi-modem
cards work without the noapic boot option. We can get one PCI-Express board to
work using IRQ 10 if we use the 'noapic' kernel boot option. The PCI/PCI-X
version works fine, and each board is assigned a different IRQ.
Steps to Reproduce:
1. Physically install 1 or more PCI-Express multi-port serial com devices in a
system with a motherboard with a PCI-Express to PCI bridge.
2. Boot the machine
3. Use lspci to view the resources assigned to the device.
Actual results: Each board is left on IRQ 10 by the OS. Even though lspci
showed that the board was assigned to IRQ 10, one board was able to be used
using IRQ 16, even though lspci said the device was using IRQ 10.
Expected results: Each board should have been assigned a new separate IRQ by
the OS. Also, Fedora should also be able to automatically configure all the
serial ports of each port on each card automatically as it does with our
PCI/PCI-X version of our board. Each serial port of our standard PCI version is
assigned a ttyS# .
Additional Info: We are the primary multi-port fax board device in the
HylaFax/Linux community, so it is very important that our PCI-Express boards
are supported. Fedora is a good starting point as it is what we use on our
test systems at our Engineering facility.
Created attachment 157485 [details]
BIOS assigned IRQ's, dmesg and messages files, lspci output(verbose)
I'm reviewing this bug as part of the kernel bug triage project, an attempt to
isolate current bugs in the fedora kernel.
I am CC'ing myself to this bug and will try and assist you in resolving it if I can.
There hasn't been much activity on this bug for a while. Could you tell me if
you are still having problems with the latest kernel?
If the problem no longer exists then please close this bug or I'll do so in a
few days if there is no additional information lodged.
As indicated previously there has been no update on the progress of this bug
therefore I am closing it as INSUFFICIENT_DATA. Please re-open if the issue
still occurs for you and I will try to assist in its resolution. Thank you for
taking the time to report the initial bug.