Messages in this thread | | | Date | Sun, 30 Mar 2008 16:03:56 -0500 | From | Jack Steiner <> | Subject | Re: [RFC 8/8] x86_64: Support for new UV apic |
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On Sun, Mar 30, 2008 at 01:23:12PM -0700, Yinghai Lu wrote: > On Wed, Mar 26, 2008 at 12:38 AM, Ingo Molnar <mingo@elte.hu> wrote: > > > > * Jack Steiner <steiner@sgi.com> wrote: > > > > > > > - obj-y += genapic_64.o genapic_flat_64.o > > > > > + obj-y += genapic_64.o genapic_flat_64.o genx2apic_uv_x.o > > > > > > > > Definitely should be a CONFIG > > > > > > Not sure that I understand why. The overhead of UV is minimal & we > > > want UV enabled in all distro kernels. OTOH, small embedded systems > > > probably want to eliminate every last bit of unneeded code. > > > > > > Might make sense to have a config option. Thoughts???? > > > > i wouldnt mind having UV enabled by default (it can be a config option > > but default-enabled on generic kernels so all distros will pick this hw > > support up), but we definitely need the genapic unification before we > > can add more features. > > config option would be reasonable. > for x86_64 > subarch already have X86_PC, X86_VSMP. > we have X86_UVSMP
If there was a significant differece between UV and generic kernels (or hardware), then I would agree. However, the only significant difference is the APIC model on large systems. Small systems are exactly compatible.
The problem with subarch is that we want 1 binary kernel to support both generic hardware AND uv hardware. This restriction is desirable for the distros and software vendors. Otherwise, additional kernel images would have to be built, released, & certified.
--- jack
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