• Linus Torvalds's avatar
    Revert "iommu/dma: Add config for PCI SAC address trick" · af3e9579
    Linus Torvalds authored
    This reverts commit 4bf7fda4.
    
    It turns out that it was hopelessly naive to think that this would work,
    considering that we've always done this.  The first machine I actually
    tested this on broke at bootup, getting to
    
        Reached target cryptsetup.target - Local Encrypted Volumes.
    
    and then hanging.  It's unclear what actually fails, since there's a lot
    else going on around that time (eg amdgpu probing also happens around
    that same time, but it could be some other random init thing that didn't
    complete earlier and just caused the boot to hang at that point).
    
    The expectations that we should default to some unsafe and untested mode
    seems entirely unfounded, and the belief that this wouldn't affect
    modern systems is clearly entirely false.  The machine in question is
    about two years old, so it's not exactly shiny, but it's also not some
    dusty old museum piece PDP-11 in a closet.
    
    Cc: Robin Murphy <robin.murphy@arm.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: John Garry <john.garry@huawei.com>
    Cc: Joerg Roedel <jroedel@suse.de>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    af3e9579
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