Re: [PATCH] RS6000 and PowerPC CPU types

[Nick Duffek <nsd at cygnus dot com>]

On 12-May-2000, Geoff Keating wrote:

>> This is not strictly correct, because (a) there are 64-bit CPUs other than
>> the 620 (e.g. the 630) and (b) the 620 can run non-XCOFF64 binaries.

>This is certainly true.  (b) is true for all 64-bit CPUs.  I don't see
>why it makes a difference.

AIX GDB displays different registers sets for different CPUs.

>This seems wrong.  It should determine the CPU being debugged by
>looking at the hardware, not looking at the object file.

I disagree.  Even if a binary is only usable on CPU type A, GDB on CPU
type B should still be able to examine that binary plus a core file
generated by CPU type A, displaying registers appropriate for CPU type A.

>It is
>meaningless to try to match a CPU model with an object file,

If the o_cputype field is set to something other than 0, then isn't it
likely that the object file is somehow specific to that CPU?

>consider
>for instance an object file that contains code for bit-blitting and
>has six routines with identical behaviour but using different CPU
>features (like altivec and 64-bit instructions).

In that case, the o_cputype field should be 0, in which case GDB would
choose the lowest common denominator.

Nick