Re: [PATCH] gdb: fix IA64 build failure of linux-nat

[Tom de Vries <tdevries@suse.de>]

On 8/17/20 10:21 AM, Simon Marchi wrote:
> On 2020-08-17 4:54 a.m., Tom de Vries wrote:
>> Hi,
>>
>> IA64 support was just obsoleted in bfd (commit 73d0dc162e "Obsolete ia64").
>>
>> So, AFAIU, this should now be built with --enable-obsolete.
>>
>> What are the consequences for gdb IA64 patches ?
>>
>> Thanks,
>> - Tom
> 
> By transitivity, I'd say that the GDB port is also obsolete.  But as long as it's in
> the tree, it's fine to accept patches to keep it building (otherwise it's useless to
> keep it in the tree).
> 

Btw, I just found in gdb/configure.tgt:
...
    echo "*** Configuration $targ is obsolete." >&2
    echo "*** Support has been REMOVED." >&2
    exit 1
...
So, maybe in gdb a target is obsolete once it's removed?  There seems to
be no separate means to declare a target obsolete before it's removed.

> If you wanted to build GDB with --target=ia64-something-something, you'll need to pass
> --enable-obsolete in order to build BFD, which is a required dependency of GDB.  When we
> pass --enable-targets=all, it builds a GDB with ia64 support without requiring that
> --enable-obsolete flag though.
> 

Hmm, I find that last bit surprising.

> Do you know what's the BFD policy for obsolete configurations?  If they wanted to get
> rid of it completely, they would need to remove GDB support too, otherwise they'd break
> the build.  So should we eventually take the lead and remove support for it first?
> 

I don't know the policy, but the discussion about ia64 took place here (
https://sourceware.org/pipermail/binutils/2020-August/112825.html ,
helpfully titled "Time to obsolete arm-symbian?" ).  It was mentioned
that there was a segfault since at least binutils 2.31 on ia64, which
had not been addressed by anybody, and "Assuming no one cares enough
about ia64 to contribute fixes for the segfaults, ia64 would remain in
binutils until after the next release, at which point the ia64 support
code might be removed".

Thanks,
- Tom

> Sergei, quick survey: do you, or someone you know actually use GDB on ia64?  Or you just
> noticed it not building because you package it?
> 
> Simon
>