Messages in this thread | | | Date | Mon, 7 Jan 2013 19:01:02 -0800 | Subject | Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is not enough ram for it | From | Yinghai Lu <> |
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On Mon, Jan 7, 2013 at 6:22 PM, Eric W. Biederman <ebiederm@xmission.com> wrote: > Yinghai I sat down and read your patch and the approach you are taking > is totally wrong.
Thanks for check the patch, did you check v3?
> > The problem is that swiotlb_init() in lib/swiotlb.c does not know how to > fail without panic'ing the system.
I did not put panic in swiotlb, now I put panic in amd_iommu ops init when it need extra swiotlb for unhandled devices by AMD IOMMU.
> > Which leaves two valid approaches. > - Create a variant of swiotlb_init that can fail for use on x86 and > handle the failure. > - Delay initializing the swiotlb until someone actually needs a mapping > from it. > > Delaying the initialization of the swiotlb is out because the code > needs an early memory allocation to get a large chunk of contiguous > memory for the bounce buffers.
ok.
> > Which means the panics that occurr in swiotlb_init() need to be delayed > until someone something actually needs bounce buffers from the swiotlb. > > Although arguably what should actually happen instead of panic() is that > swiotlb_map_single should simply fail early when it was not possible to > preallocate bounce buffers.
do you mean: actually needed dma buffer is much less than swiotlb buffer aka 64M?
Yinghai
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