Re: [RFC] dl-procinfo and HWCAP_IMPORTANT support for powerpc

[Steve Munroe <sjmunroe at us dot ibm dot com>]

Christoph Hellwig <hch@lst.de> wrote on 12/15/2005 06:36:01 AM:

> > We have made a deliberate decision not to identify older processor
> > generations (POWER3, G4). They are no longer in production and/or are
> > adequately covered by the current glibc implementation. They will 
continue
> > to be supported by current base/default implementation (as defined by 
gcc
> > options -mcpu=powerpc for 32-bit and -mcpu=powerpc64 for 64-bit).
> 
> That's not true.  G4, G3 and even G2-based microarchitectures are still
> in production at motorola.  Not to mention things like the 8xx.

Did you miss the "or are adequately covered by the current glibc 
implementation" part?

Note: I did not say they are not supported, I did say that I (personally) 
was not going to do anything extra for them. I have my hands full keeping 
on top of the current IBM products (along with all my other jobs).

But you should be supporting my efforts on this and the related --with-cpu 
support. I have done all the heavy lifting to enable the general 
mechanism. If you are supportive of this effort, then please say so.

If you are vitally interested in supporting G2, G3, G4 then you will need 
to:

1) Negotiate with Paul Mackerras to get bits allocated in AT_HWCAP from 
the kernel.

2) Verify that gcc has the -mcpu= support you need. If not you need to 
negotiate with David Edelsohn to get any -mcpu= support and __ARCH_ 
macro's you might need.

3) Provide detail analysis and justification of why the (widely used) 
processor/chip that you want to support is not well served by the current 
(default) implementation.

4) Provide optimized implementations of high use functions where needed.

Then we can work together to update dl-procinfo to support what you come 
up with.



Steven J. Munroe
Linux on Power Toolchain Architect
IBM Corporation, Linux Technology Center