Messages in this thread | | | Date | Sun, 6 Oct 2013 11:42:27 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86: Don't make AMD_GART depend on EXPERT and default y |
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* Andi Kleen <andi@firstfloor.org> wrote:
> From: Andi Kleen <ak@linux.intel.com> > > The AMD_GART driver was made EXPERT/EMBEDDED a long time > ago to avoid unbootable 64bit systems with 32bit only devices. > > This was before swiotlb was there, which does the job > of this fallback today. SWIOTLB is always on, so systems > should always boot. > > The drawback is that every system has to compile that > driver in (it cannot be a module). > > Also: > - Newer AMD CPUs (the APUs) don't seem to have AMD_GART support > at all anymore. > - Newer AMD platforms have a much better real IOMMU > - The AMD GART driver was never very good (lots of overhead, e.g. > in flushing due to some workarounds) and it's doubtful it's really > better than SWIOTLB. > - On older K8 systems it didn't even work with all chipsets. > - The 32bit device bounce buffer case should be rare/ > non performance critical these days anyways. > - On non AMD systems it is not needed at all. > > So drop the EXPERT dependency on AMD_GART and remove the > default y. The driver can be still compiled in, just > it's an explicit decision now, and people who don't want > it can unselect it. > > I also clarified the description a bit. > > This allows to save ~8K text on most modern x86-64 systems. > > Cc: bp@suse.de > Signed-off-by: Andi Kleen <ak@linux.intel.com>
Btw., this is a perfect changelog!
Thanks,
Ingo
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