On Tue, 7 May 2024 01:34:59 +0000
"T.J. Mercier" <tjmercier@xxxxxxxxxx> wrote:
> Commit 20347fca71a3 ("swiotlb: split up the global swiotlb lock") added
> the ability to specify the number of SWIOTLB areas, but boot-options.rst
> was not updated as part of that commit.
>
> Reported-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
> Fixes: 20347fca71a3 ("swiotlb: split up the global swiotlb lock")
> Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx>
> ---
> Documentation/arch/x86/x86_64/boot-options.rst | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/arch/x86/x86_64/boot-options.rst b/Documentation/arch/x86/x86_64/boot-options.rst
> index a37139d1752f..18161657b301 100644
> --- a/Documentation/arch/x86/x86_64/boot-options.rst
> +++ b/Documentation/arch/x86/x86_64/boot-options.rst
> @@ -287,9 +287,11 @@ iommu options only relevant to the AMD GART hardware IOMMU:
> iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
> implementation:
>
> - swiotlb=<slots>[,force,noforce]
> + swiotlb=<slots>[,<areas>,force,noforce]
This is not quite how this parameter is parsed. All the following
specifications are valid:
- swiotlb=512 // only slots
- swiotlb=,4 // only areas
- swiotlb=512,4 // slots and areas
- swiotlb=force // default size
- swiotlb=512,force // default areas
- swiotlb=512,4,force // explicitly specify everything
I believe the syntax should be somethig like:
swiotlb={ | [<slots>][,<areas>],}{ force | noforce }
Petr T
> <slots>
> Prereserve that many 2K slots for the software IO bounce buffering.
> + <areas>
> + Number of SWIOTLB areas with their own lock. Must be a power of 2.
> force
> Force all IO through the software TLB.
> Hardware IOMMU implementations can use SWIOTLB bounce buffering in
