Re: [PING][PATCH,v5][AArch64] MTE corefile support

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

On 2021-07-14 9:07 a.m., Catalin Marinas wrote:
> On Sun, Jul 11, 2021 at 07:22:00AM -0700, Joel Brobecker wrote:
>> Luis is trying to have this new feature ready for the GDB 11.1
>> release. As I understand it, the AArch64-specific part has already
>> been approved, so he's waiting for someone to review the rest of
>> the changes. Is there a Global Maintainer who would feel comfortable
>> doing so and who would have the time?
> 
> I'm a Linux kernel maintainer, so not much for me to review on the gdb
> front. But feedback from the gdb maintainers would be appreciated.
> 
> W.r.t. upstreaming the feature in gdb, I'd wait until the Linux
> counterpart is merged. We agreed in principle on the ABI but I wouldn't
> consider it stable until the feature hits a kernel release.

I reviewed a few of the previous iterations, and there were only really
some nits remaining, so I am confident that this version is OK, from a
GDB point of view.

ABI-wise, I tend to agree with Catalin: as long as it's not in a
released kernel, the format *could* change.  But is it a problem in
practice?  Let's say this happens:

 - We merge support for MTE core files in GDB 11
 - The format gets changed, merged and released in a kernel
 - We fix GDB 12 based on the new format

Then GDB 11 users end up with a GDB that can't read MTE notes.  But had
we not merged the support for it, they would also end up with a GDB that
can't read MTE notes.  In both cases, we'll tell them "upgrade to GDB
12" (once it's released).

If we merge support for MTE in core files now and if the format
doesn't change, everybody is happy.  I guess it depends on how likely it
is that the format is going to change.

Simon