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| author | Christian Melki <christian.melki@t2data.com> | 2015-10-05 17:31:33 +0200 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2015-10-07 21:31:35 +0200 |
| commit | 9d99c7123c9af5f47a2037933a3ffaec3e37efad (patch) | |
| tree | 73617b729d320323cc3f9362fc1ce1b5acb9d847 /arch/x86 | |
| parent | Linux 4.3-rc4 (diff) | |
| download | linux-9d99c7123c9af5f47a2037933a3ffaec3e37efad.tar.xz linux-9d99c7123c9af5f47a2037933a3ffaec3e37efad.zip | |
swiotlb: Enable it under x86 PAE
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 a6dfa128ce5c414ab46b1d690f7a1b8decb8526d
"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: Christian Melki <christian.melki@t2data.com>
Signed-off-by: Christian Melki <christian.melki@t2data.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 328c8352480c..96d058a87100 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1308,6 +1308,7 @@ config HIGHMEM config X86_PAE bool "PAE (Physical Address Extension) Support" depends on X86_32 && !HIGHMEM4G + select SWIOTLB ---help--- PAE is required for NX support, and furthermore enables larger swapspace support for non-overcommit purposes. It |