(For some reason the "Date:" header of this message is 16 hours into the
future. Ie, it claims to be for (UTC) 2015-01-26, 19.30 but actually was
probably sent around (UTC) 2015-01-26, 03.30. This made this message
stick at the top of the mail folder it ended up in. And that was about
the only reason why I even scanned it.)
On Tue, 2015-01-27 at 03:30 +0800, xiaomin1 wrote:
> The maximum of SW-IOMMU is limited to 2^11*128 = 256K.
> While in different platform and different requirements this seems improper.
> So modify the IO_TLB_SEGSIZE to configtable is make sense.
configurable?
Ditto for the summary.
> Example:
> If 1M bytes are requied. There has an error like.
required one will run into an error like:
or something similar.
> [ 33.293120] DMA: Out of SW-IOMMU space for 1048576 bytes at device gadget
So in order to solve that and use 1M this new option needs to be set at
512?
> Signed-off-by: Chuansheng Liu <chuansheng....@intel.com>
> Signed-off-by: Zhang Dongxing <dongxing.zh...@intel.com>
> Signed-off-by: xiaomin1 <xiaoming.w...@intel.com>
> ---
> include/linux/swiotlb.h | 2 +-
> lib/Kconfig | 4 ++++
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
> index e7a018e..5ab10b9 100644
> --- a/include/linux/swiotlb.h
> +++ b/include/linux/swiotlb.h
> @@ -14,7 +14,7 @@ extern int swiotlb_force;
> * must be a power of 2. What is the appropriate value ?
> * The complexity of {map,unmap}_single is linearly dependent on this value.
> */
> -#define IO_TLB_SEGSIZE 128
> +#define IO_TLB_SEGSIZE CONFIG_DEFAULT_IO_TLB_SEGSIZE
>
> /*
> * log of the size of each IO TLB slab. The number of slabs is command line
> diff --git a/lib/Kconfig b/lib/Kconfig
> index 54cf309..76f1108 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -518,4 +518,8 @@ source "lib/fonts/Kconfig"
> config ARCH_HAS_SG_CHAIN
> def_bool n
>
> +config DEFAULT_IO_TLB_SEGSIZE
> + int
No "prompt", so to change this value one needs to edit the .config
manually. Is that intended?
> + default 128
According to include/linux/swiotlb.h this needs to be a power of 2.
Shouldn't that be explained here too? Ditto the 2K unit size. And should
a range of useful values be specified?
(These are not rhetorical questions: I know nothing about all this. This
also means I might just not be part of the intended audience for this
option.)
> endmenu
Paul Bolle
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