On Tue, 16 Mar 2010 14:28:09 -0500
Becky Bruce [off-list ref] wrote:

On Mar 16, 2010, at 5:08 AM, FUJITA Tomonori wrote:

quoted

On Tue, 16 Mar 2010 06:58:41 +0100
Albert Herranz [off-list ref] wrote:

quoted

FUJITA Tomonori wrote:

quoted

On Fri, 12 Mar 2010 20:12:40 +0100
Albert Herranz [off-list ref] wrote:

quoted

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 <redacted>
---
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.

Hmm, why swiotlb_late_init_with_default_size()?

Why can't you initialize swiotlb in mem_init() like this (only compile
tested)? Any time before freeing bootmem works for swiotlb.

This is an oops in the original patchset -  I think it should be fine  
to move the swiotlb_init later as Fujita suggests, at least for 32-bit  
powerpc.  I just booted this on mpc8641 and everything seems OK.

Thanks!

I'll resend this patch in the proper format. This patch fixes the
problem that powerpc ignores swiotlb boot options so we can merge it
independent of Albert's patchset.