Re: [PATCH v2 1/2] perf bench: Fix initialization of union

[Leo Yan <leo.yan@arm.com>]

On Thu, Feb 19, 2026 at 10:38:57AM +0000, James Clark wrote:
> 
> 
> On 19/02/2026 10:36 am, James Clark wrote:
> > 
> > 
> > On 19/02/2026 12:44 am, Namhyung Kim wrote:
> > > Recent compilers don't initialize all members (or the largest member) in
> > > an union.  Instead it seems to set the first member only.  So some perf
> > > bench output shows invalid numbers like below on my system with GCC 15.
> > 
> > I couldn't find V1 of this so I wasn't sure if it was discussed already,
> > but wasn't the plan to fix this with a compiler option:
> > 
> > https://lore.kernel.org/linux-perf-users/20250319110454.3230687-1-leo.yan@arm.com/
> > 
> > and
> > 
> > https://lore.kernel.org/linux-perf-users/20250320105235.3498106-1-leo.yan@arm.com/
> 
> Oh I see V1 was only the second patch, that's why I couldn't find it.

Thanks for bringing up this, James.  The latest patch would be:

https://lore.kernel.org/lkml/20250402173056.829400-1-leo.yan@arm.com/

This patch intends to apply the option across tools, but no response
from the maintainers.  Seems to me, it may be good enought to apply the
option to perf first.

Thanks,
Leo