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    SubjectRe: [PATCH 0/3] Early use of boot service memory
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    On Mon, Nov 18, 2013 at 5:32 PM, H. Peter Anvin <hpa@zytor.com> wrote:
    > On 11/15/2013 10:30 AM, Vivek Goyal wrote:
    >>
    >> And IOMMU support is very flaky with kdump. And IOMMU's can be turned
    >> off at command line. And that would force one to remove crahkernel_low=0.
    >> So change of one command line option forces change of another. It is
    >> complicated.
    >>
    >> Also there are very few systems which work with IOMMU on. A lot more
    >> which work without IOMMU. We have all these DMAR issues and still nobody
    >> has been able to address IOMMU issues properly.
    >>
    >
    > Why do we need such a big bounce buffer for kdump swiotlb anyway?
    > Surely the vast majority of all dump devices don't need it, so it is
    > there for completeness, no?

    Yes, because normal path will need that 64M+32k default.

    We may reduce that amount to 16M or 18M and in second kernel let
    allocate less for swiotlb.

    Thanks

    Yinghai


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