| Message ID | 1268421166-4791-6-git-send-email-albert_herranz@yahoo.es (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Fri, 12 Mar 2010 20:12:40 +0100 Albert Herranz <albert_herranz@yahoo.es> wrote: > The current SWIOTLB code uses a default of 64MB for the IO TLB area. > This size can be influenced using a kernel command line parameter "swiotlb". > Unfortunately, the parsing of the kernel command line is done _after_ the > swiotlb is initialized on some architectures. > > This patch adds a new function swiotlb_set_default_size() which can be used > before swiotlb_init() to indicate the desired IO TLB area size in bytes. > > This will be used later to implement a smaller IO TLB on the Nintendo Wii > video game console which just comes with 24MB + 64MB of RAM. > > CC: linuxppc-dev@lists.ozlabs.org > CC: linux-kernel@vger.kernel.org > CC: x86@kernel.org > CC: linux-ia64@vger.kernel.org > Signed-off-by: Albert Herranz <albert_herranz@yahoo.es> > --- > include/linux/swiotlb.h | 2 ++ > lib/swiotlb.c | 20 ++++++++++++++++++++ > 2 files changed, 22 insertions(+), 0 deletions(-) Please fix the powerpc swiotlb initialization instead. Calling swiotlb_init() before parsing kernel parameters sounds wrong. Any reasons why you can't fix it?
FUJITA Tomonori wrote: > On Fri, 12 Mar 2010 20:12:40 +0100 > Albert Herranz <albert_herranz@yahoo.es> wrote: > >> The current SWIOTLB code uses a default of 64MB for the IO TLB area. >> This size can be influenced using a kernel command line parameter "swiotlb". >> Unfortunately, the parsing of the kernel command line is done _after_ the >> swiotlb is initialized on some architectures. >> >> This patch adds a new function swiotlb_set_default_size() which can be used >> before swiotlb_init() to indicate the desired IO TLB area size in bytes. >> >> This will be used later to implement a smaller IO TLB on the Nintendo Wii >> video game console which just comes with 24MB + 64MB of RAM. >> >> CC: linuxppc-dev@lists.ozlabs.org >> CC: linux-kernel@vger.kernel.org >> CC: x86@kernel.org >> CC: linux-ia64@vger.kernel.org >> Signed-off-by: Albert Herranz <albert_herranz@yahoo.es> >> --- >> include/linux/swiotlb.h | 2 ++ >> lib/swiotlb.c | 20 ++++++++++++++++++++ >> 2 files changed, 22 insertions(+), 0 deletions(-) > > Please fix the powerpc swiotlb initialization instead. > > Calling swiotlb_init() before parsing kernel parameters sounds > wrong. Any reasons why you can't fix it? > I think that this would be better asked by a PowerPC maintainer. Ben? If this is really a problem the swiotlb late init may be a solution too in this particular case. Thanks, Albert
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 3954228..2af6a45 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -22,6 +22,8 @@ extern int swiotlb_force; */ #define IO_TLB_SHIFT 11 +extern size_t __init swiotlb_set_default_size(size_t size); + extern void swiotlb_init(int verbose); extern void *swiotlb_alloc_boot(size_t bytes, unsigned long nslabs); diff --git a/lib/swiotlb.c b/lib/swiotlb.c index 8f2dad9..dbeca50 100644 --- a/lib/swiotlb.c +++ b/lib/swiotlb.c @@ -117,6 +117,26 @@ setup_io_tlb_npages(char *str) __setup("swiotlb=", setup_io_tlb_npages); /* make io_tlb_overflow tunable too? */ +/** + * swiotlb_set_default_size() - set the default size for the IO TLB + * @size: size in bytes of the IO TLB + * + * A platform can use this function to change the default size of the + * IO TLB when the default of 64MB is not suitable. + * This function must be called before swiotlb_init(). + * + * Note that on some platforms this is the only way to influence the + * size of the IO TLB, as the command line may be parsed _after_ the + * IO TLB is initialized. + */ +size_t __init swiotlb_set_default_size(size_t size) +{ + size_t previous_size = io_tlb_nslabs << IO_TLB_SHIFT; + + io_tlb_nslabs = size >> IO_TLB_SHIFT; + return previous_size; +} + void * __weak __init swiotlb_alloc_boot(size_t size, unsigned long nslabs) { return alloc_bootmem_low_pages(size);
The current SWIOTLB code uses a default of 64MB for the IO TLB area. This size can be influenced using a kernel command line parameter "swiotlb". Unfortunately, the parsing of the kernel command line is done _after_ the swiotlb is initialized on some architectures. This patch adds a new function swiotlb_set_default_size() which can be used before swiotlb_init() to indicate the desired IO TLB area size in bytes. This will be used later to implement a smaller IO TLB on the Nintendo Wii video game console which just comes with 24MB + 64MB of RAM. CC: linuxppc-dev@lists.ozlabs.org CC: linux-kernel@vger.kernel.org CC: x86@kernel.org CC: linux-ia64@vger.kernel.org Signed-off-by: Albert Herranz <albert_herranz@yahoo.es> --- include/linux/swiotlb.h | 2 ++ lib/swiotlb.c | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+), 0 deletions(-)