[Xen-devel] Workaround for the corrupted Intel X48 DMAR table

["Neo Jia" <neojia@xxxxxxxxx>]

hi,

I am trying the Xen unstable on X48 chipset these days but it failed due to an corrupted RMRR table in the ACPI. The following is the acpi dump of DMAR.

DMAR @ 0x7fef1000
  0000: 44 4d 41 52 20 01 00 00 01 d1 49 4e 54 45 4c 20  DMAR .....INTEL 
  0010: 44 58 34 38 42 54 32 20 12 06 00 00 4d 53 46 54  DX48BT2 ....MSFT
  0020: 13 00 00 01 23 00 00 00 00 00 00 00 00 00 00 00  ....#...........
  0030: 00 00 18 00 00 00 00 00 00 00 b0 fe 00 00 00 00  ................
  0040: 01 08 00 00 00 00 1b 00 00 00 20 00 00 00 00 00  .......... .....
  0050: 00 10 b0 fe 00 00 00 00 01 08 00 00 00 00 02 00  ................
  0060: 01 08 00 00 00 00 02 01 00 00 28 00 00 00 00 00  ..........(.....
  0070: 00 20 b0 fe 00 00 00 00 01 08 00 00 00 00 03 00  . ..............
  0080: 01 08 00 00 00 00 03 02 01 08 00 00 00 00 03 03  ................
  0090: 00 00 10 00 01 00 00 00 00 30 b0 fe 00 00 00 00  .........0......
  00a0: 01 00 58 00 00 00 00 00 00 00 0e 00 00 00 00 00  ..X.............
  00b0: ff ff 0e 00 00 00 00 00 01 08 00 00 00 00 1d 00  ................
  00c0: 01 08 00 00 00 00 1d 01 01 08 00 00 00 00 1d 02  ................
  00d0: 01 08 00 00 00 00 1d 07 01 08 00 00 00 00 1a 00  ................
  00e0: 01 08 00 00 00 00 1a 01 01 08 00 00 00 00 1a 02  ................
  00f0: 01 08 00 00 00 00 1a 07 01 00 28 00 00 00 00 00  ..........(.....
  0100: 00 00 00 80 00 00 00 00 ff ff ff 7f 00 00 00 00  ................
  0110: 01 08 00 00 00 00 02 00 01 08 00 00 00 00 02 01  ................

In line:  0100: 00 00 00 80 00 00 00 00 ff ff ff 7f 00 00 00 00, the RMRR reserved memory region starting address is even higher than its limit address.

Is there anyway to do a software workaround for this issue? I tried to simply ignore that entry in the "acpi_parse_one_rmrr" function, but I hit a panic in function "iommu_enable_translation".

Thanks,
Neo
-- 
I would remember that if researchers were not ambitious 
probably today we haven't the technology we are using! 

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