On Thu, Nov 05, 2009 at 09:39:36AM +0800, Wu Zhangjin wrote:
> > > > We have other systems where 32-bit kernel support is just remarkably
> > > > ugly.
> > > > We've dropped 32-bit support for the SGI IP32 aka O2 - nobody seems to
> > > > even
> > > > have really noticed that. The Sibyte systems would be good candidates
> > > > to do
> > > > the same as accesses to outside the 32-bit address space are needed very
> > > > frequently.
> > > >
> > >
> > > So, we really remove the 32bit support?
> > >
> > > 1312 config CPU_LOONGSON2
> > > 1313 bool
> > > 1314 select CPU_SUPPORTS_32BIT_KERNEL --> remove it?
> > > 1315 select CPU_SUPPORTS_64BIT_KERNEL
> > > 1316 select CPU_SUPPORTS_HIGHMEM
> > >
> > > If you all agree, I will send a new patch to remove the above line and
> > > resend the corresponding patches without 32bit support, and removed the
> > > relative CONFIG_64BIT lines in the patches too.
> > If you need highmem with 32-bit (and with Loongson systems I assume that
> > virtually all systems will have enough RAM to require that) then you're
> > almost certainly better off going 64-bit. Highmem takes a performance toll
> > which for some workloads can be very significant. And while highmem won't
> > go away any time soon it's nothing kernel performance is being tuned for,
> > so it's only going to get worse into the future so I'd not waste time on
> > highmem unless I have to.
> What I have mentioned: "perhaps some guys need the 32bit version" here
> means, perhaps some embedded systems without enough memory and enough
> storage space may need the 32bit version, they not need highmem and
> also, the 32bit version will save some storage space for them. and I
> have used the 32bit version on my box and notebook(of course, only for
> experiments), no obvious problems.
> Reserve the 32bit version as an choice and select 64bit by default in
> the default config file?
No problem - I was just expressing my expressing my experiences on the
usefulness of supporting both settings. One usually tends up favored, the
other little used.