Re: [PATCH v3] Remove stale pre-AIX-7.2 compatibility guards

[Simon Marchi <simon.marchi@polymtl.ca>]

On 9/23/26 8:53 AM, Ulrich Weigand wrote:
> Simon Marchi <simon.marchi@polymtl.ca> wrote:
>> On 9/22/26 12:52 AM, Aditya Vidyadhar Kamath wrote:
>>> From: Aditya Kamath <Aditya.Kamath1@ibm.com>
>>>
>>> GDB now requires AIX 7.2 as the minimum supported version and will
>>> support AIX 7.2 TL5, AIX 7.3 and upcoming AIX releases.  Remove
>>> dead compatibility code that existed only for older releases.
>>>
>>> Remove the HAVE_DECL_GETTHRDS configure check since aix-thread.c was
>>> the last
>>> user of that macro.  Merge ptrace64aix and ptrace32 into a single
>>> ptrace_aix function since they became identical after this
>>> cleanup, and collapse all call sites that branched on arch64 just to
>>> pick between the two.  Also clean up rs6000-aix-nat.c by removing
>>> the
>>> ARCH3264 and HAVE_PTRACE64 guards along with the ptracex fallback in
>>> rs6000_ptrace32 and rs6000_ptrace64, which are now simple wrappers
>>> around ptrace64.
>>>
>>> Also as per >https://www.ibm.com/docs/en/aix/7.2.0?topic=p-ptrace-
>> ptracex-ptrace6>4-subroutine 
>>> ptrace64 will also support 32-bit debugees.
>>
>> On this page I see:
>>
>>     For ptracex or ptrace64: If the debuggee is a 32-bit process, the
>>     options that refer to GPRs or SPRs fail with errno = EIO
>>
>> And I see that in the patch, you call ptrace64 to read registers
>> (PTT_READ_GPRS) for 32 bit processes.  How does that work?
> 
> I think Simon is correct here.  For GPRS access, I understand only
> the following options are supported:
> 
> ptrace: 32- or 64-bit GDB, 32-bit inferior
> ptracex: 32-bit GDB, 64-bit inferior
> ptrace64: 64-bit GDB, 64-bit inferior
> 
> As I understand, the current set of indirections is intended to
> cover that space - for a 32-bit inferior, you call ptrace, and
> for a 64-bit inferior you call either ptracex or ptrace64,
> depending on whether GDB is built as 64-bit.

Ideally, we wouldn't just guess.  Do you run the testsuite on AIX?  If
so, you should be able to run it in a mode that builds the test programs
as 32-bit programs.  For example:

  $ make check RUNTESTFLAGS='--target_board "unix/-m32"

Taken from:

  https://sourceware.org/gdb/wiki/TestingGDB#Changing_the_compiler_used_to_build_the_testcases

> Why do you think we can simplify this?  I guess we could make
> possibly make the assumption that GDB itself is always built
> as 64-bit these days, but then we still have to select between
> ptrace and ptrace64 at the least ...

I think that requiring GDB to be built as 64-bit program would be
reasonable (if so you should add a static check in the source for that).

Simon