Re: Boot hangs "Probing PCI hardware"

>>>>> On Wed, 03 Apr 2002 19:10:11 +0900, Tatsuya Tsurukawa <[email protected]> said:

  Tatsuya> There are some BAR operations in pci_read_bases() function
  Tatsuya> of pci.c to get memory and IO space ranges assigned for
  Tatsuya> each PCI device by writing 0xffffffff on BAR and reading it
  Tatsuya> again. If an interrupt from SAPIC occurs during BAR
  Tatsuya> operations, the first PCI Bus hangs.

Interesting.

  Tatsuya> In this case, the video device gets 64MB memory space from
  Tatsuya> 0xFC000000 to 0xFFFFFFFF improperly, and it conflicts with
  Tatsuya> System reserve region (0xFCxxxxxx - 0xFExxxxxx) for SAPIC
  Tatsuya> interrupt messages. After that the video device reacts to
  Tatsuya> an SAPIC interrupt improperly.

  Tatsuya> According to PCI specifications, it is necessary to disable
  Tatsuya> Memory IO target function during BAR operations by setting
  Tatsuya> zero to bit0/1 of PCI_COMMAND, but current pci_read_bases()
  Tatsuya> doesn't do that.

Makes sense.  Just for completeness (and to save me some time), could
you point out the section in the PCI spec that requires this?

  Tatsuya> I'd like to provide the following patch, and I've already
  Tatsuya> found it works well on both RHL7.2 and Kernel-2.4.18.

The patch looks mostly good to me, except that I think it would be better
to replace:

        pci_write_config_word(dev, PCI_COMMAND, pcicmd_sv & 0xfffc);

with:

        pci_write_config_word(dev, PCI_COMMAND,
			pcicmd_sv & ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY));

also, a comment pointing to the appropriate PCI section might be
helpful.

Are you going to submit this directly to the PCI maintainer?  Even
though it happens to show on ia64, it's a generic bug.  (And why not
cc [email protected] while you're at it? ;-)

Thanks,

	--david