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    SubjectRe: [patch 01/22] AMD IOMMU: enable device isolation per default
    On Fri 2008-12-19 12:21:37, Joerg Roedel wrote:
    > On Thu, Dec 18, 2008 at 02:00:15PM +0100, Pavel Machek wrote:
    > > On Tue 2008-12-16 16:03:53, Greg KH wrote:
    > > > 2.6.27-stable review patch. If anyone has any objections, please let us know.
    > > >
    > > > ------------------
    > > >
    > > > From: Joerg Roedel <joerg.roedel@amd.com>
    > > >
    > > > commit 3ce1f93c6d53c3f91c3846cf66b018276c8ac2e7 upstream.
    > > >
    > > > Impact: makes device isolation the default for AMD IOMMU
    > > >
    > > > Some device drivers showed double-free bugs of DMA memory while testing
    > > > them with AMD IOMMU. If all devices share the same protection domain
    > > > this can lead to data corruption and data loss. Prevent this by putting
    > > > each device into its own protection domain per default.
    > > >
    > > > Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
    > > > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    > >
    > > This does not look like 'fix for a serious bug' to
    > > me. stable_kernel_rules.txt says '...not a "this could be a problem"
    > > type thing'.
    >
    > So you don't consider lost data because your filesystem is corrupted
    > as a problem? This is exactly what can happen (and I suffered from it
    > one time) if you use IOMMU with a buggy driver (typically a network card
    > driver).

    If you have buggy driver, _you have to fix the driver_, not work
    around it by iommu magic that only few machines can do.

    So this fixes nothing. (But it helps mask bugs in other pieces of
    code/hw. Good. But for stable?)

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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