Hi,

I just want to report that the PAT support in x86/mm causes crashes
on two of my test machines. On both boxes the SATA detection does
not work when the PAT support is patched into the kernel.

Symptoms are as follows -- best described by a diff between the
two boot.logs:

# diff boot-failing.log boot-working.log

-Linux version 2.6.24-rc8-ga9f7faa5 (root@hunter) (gcc version ...
+Linux version 2.6.24-rc8-g2ea3cf43 (root@hunter) (gcc version ...
...
 early_iounmap(ffffffff82a0b000, 00001000)
-early_ioremap(000000000000c000, 00001000) => -000002103394304
-early_iounmap(ffffffff82a0c000, 00001000)
 early_iounmap(ffffffff82808000, 00001000)
...
-ACPI: PCI interrupt for device 0000:00:12.0 disabled
-sata_sil: probe of 0000:00:12.0 failed with error -12
+scsi0 : sata_sil
+scsi1 : sata_sil
+ata1: SATA max UDMA/100 mmio m512@0xc0403000 tf 0xc0403080 irq 22
...
-AC'97 space ioremap problem
-ACPI: PCI interrupt for device 0000:00:14.5 disabled
-ATI IXP AC97 controller: probe of 0000:00:14.5 failed with error -5
 ALSA device list:
-  No soundcards found.
+  #0: ATI IXP rev 80 with ALC655 at 0xc0403800, irq 17
...
-VFS: Cannot open root device "sda1" or unknown-block(0,0)
-Please append a correct "root=" boot option; here are the available partitions:
-1600    4194302 hdc driver: ide-cdrom
-Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
+kjournald starting.  Commit interval 5 seconds
+EXT3-fs: mounted filesystem with ordered data mode.
+VFS: Mounted root (ext3 filesystem) readonly.
...

   <snip>
 
The second test machine uses ahci. But the symptoms are similar.

I performed a git-bisect on x86/mm. Last commit that worked for me was

2ea3cf43fddecbfd66353caafdf73ec21ea3760b (x86: fix early_ioremap() ISA window)

The subsequent commits for PAT support introduced the problem.
I noticed that PAT should be disabled by default, but obviously the patches
still have some side-effect. (Maybe ioremap changes lead to the problem?)

Boot-logs are attached:

  boot-failing.log for x86/mm as of v2.6.24-rc8-672-ga9f7faa
  boot-working.log for x86/mm as of v2.6.24-rc8-621-g2ea3cf4

Hopefully it helps to track down the problem.
Maybe someone has an idea why the PAT patches are causing that
ominous "PCI interrupt for device ... disabled" messages.


Thanks and regards,

Andreas