1. 11 Oct, 2015 6 commits
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  4. 08 Oct, 2015 11 commits
  5. 07 Oct, 2015 1 commit
    • Christian Melki's avatar
      swiotlb: Enable it under x86 PAE · 9d99c712
      Christian Melki authored
      Most distributions end up enabling SWIOTLB already with 32-bit
      kernels due to the combination of CONFIG_HYPERVISOR_GUEST|CONFIG_XEN=y
      as those end up requiring the SWIOTLB.
      
      However for those that are not interested in virtualization and
      run in 32-bit they will discover that: "32-bit PAE 4.2.0 kernel
      (no IOMMU code) would hang when writing to my USB disk. The kernel
      spews million(-ish messages per sec) to syslog, effectively
      "hanging" userspace with my kernel.
      
      Oct  2 14:33:06 voodoochild kernel: [  223.287447] nommu_map_sg:
      overflow 25dcac000+1024 of device mask ffffffff
      Oct  2 14:33:06 voodoochild kernel: [  223.287448] nommu_map_sg:
      overflow 25dcac000+1024 of device mask ffffffff
      Oct  2 14:33:06 voodoochild kernel: [  223.287449] nommu_map_sg:
      overflow 25dcac000+1024 of device mask ffffffff
      ... etc ..."
      
      Enabling it makes the problem go away.
      
      N.B. With a6dfa128
      "config: Enable NEED_DMA_MAP_STATE by default when SWIOTLB is selected"
      we also have the important part of the SG macros enabled to make this
      work properly - in case anybody wants to backport this patch.
      Reported-and-Tested-by: default avatarChristian Melki <christian.melki@t2data.com>
      Signed-off-by: default avatarChristian Melki <christian.melki@t2data.com>
      Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      9d99c712