Re: Re* 2.54.0-rc1 NO_WRITEV=Nope does not work

From: Jeff King <peff@peff.net>
Date: Apr 9, 2026, 22:21 UTC
Message-ID: <20260409222131.GA3130242@coredump.intra.peff.net>
In-Reply-To: <xmqqmrzbreav.fsf_-_@gitster.g>

On Thu, Apr 09, 2026 at 02:53:28PM -0700, Junio C Hamano wrote:

Show 5 quoted lines

> > Yuck. I think for 2.54 we either have to truly implement MAX_IO_SIZE
> > support, or we have to revert the use of writev() in send_sideband()
> > until we do.
> 
> Sigh again.

Yeah, I feel the same way. :(

I would be happy if somebody could prove me wrong, though.

Show 8 quoted lines

> $ git log -Swritev --oneline 8023abc632^..
> 89152af176 cmake: use writev(3p) wrapper as needed
> 26986f4cba sideband: use writev(3p) to send pktlines
> 1970fcef93 wrapper: introduce writev(3p) wrappers
> 3b9b2c2a29 compat/posix: introduce writev(3p) wrapper
> 
> Reverting them gave us the following patch relative to the tip of
> 'master'.

If we are planning to improve the topic post-release (and I think that is a good idea), then we can do a much smaller revert. If we just revert 26986f4cba (sideband: use writev(3p) to send pktlines, 2026-03-13), then nobody calls writev (neither the real one nor our fallback). The wrappers are dead code until we bring it back, but it may make things easier for fixing post-2.54.

-Peff