[Bug tdep/30340] [gdb/aarch64] gdb doesn't handle unknown debug architecture versions gracefully (TCL errors on gdb.base/watchpoint-unaligned.exp with KVM)

["aburgess at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30340

Andrew Burgess <aburgess at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
                 CC|                            |aburgess at redhat dot com

--- Comment #26 from Andrew Burgess <aburgess at redhat dot com> ---
We've discussed this bug a little on IRC, but I wanted to drop a note of the
current plan.

I feel there's two issues here, one if the TCL error.  This occurs because a
TCL variable ends up not being initialized when one of the gdb_test_multiple
calls fails.

Then there's a different (but related) question of why the gdb_test_multiple
call failed.

I think we should fix the uninitialized variable issue separately to digging
into the question of "why" the test is failing.  There are many reasons why a
gdb_test_multiple call could fail - even if we spot and catch this specific
case, the gdb_test_multiple could fail for some other reason tomorrow, and then
the TCL error would be back.  Alexandra has a patch on the list which addresses
the TCL issue which we can merge sooner rather than later[1].

As for why the test is failing in this case, it appears to be some ptrace call
that is returning unexpected results.  Right now it's not clear if this is a
legitimate result that GDB/the testsuite is just not expecting, or if this
unexpected result represents a bug in the software stack -- the issue was seen
on a virtual machine using Red Hat modified .... well ... everything -- and
everything is of various ages.  We're currently digging into this issue within
RH trying to figure out where the unexpected result is coming from, and will
update here once we know more information.

[1] https://sourceware.org/pipermail/gdb-patches/2023-April/199092.html

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