klibc - Feb 2026 - [PATCH net-next v2 0/4] net: uapi: Provide an UAPI definition of 'struct sockaddr'

On Sat, Jan 31, 2026 at 09:25:17AM -0800, Jakub Kicinski
wrote:
> On Sat, 31 Jan 2026 11:26:32 +0100 Thomas Wei?schuh wrote:
> > Jan 30, 2026 17:17:46 Jakub Kicinski <kuba at kernel.org>:
> > 
> > > On Fri, 30 Jan 2026 11:34:15 +0100 Thomas Wei?schuh wrote:  
> > >> Some of them get broken by the new 'struct sockaddr',
but some others are
> > >> already broken just by the new transitive inclusion of
libc-compat.h.
> > >> So any header starting to use the compatibility machinery may
trigger breakage
> > >> in code including UAPI headers before libc header, even for
completely new type
> > >> definitions which themselves would not conflict with libc.  
> > >
> > > Let's split the uAPI header changes from any selftest
changes.
> > > If you're saying the the selftests no longer build after the
uAPI
> > > header changes then of course we can't apply the patches.  
> > 
> > Yes, the selftests don't build anymore after the uAPI changes.
> > 
> > "can't apply" as in
> > * "can't apply separately"
> > * "are unacceptable in general"
> 
> this one
> 
> > * "are too late for this cycle"
> > ?
> > 
> > None of this is urgent.
> > We can do the selftests in one cycle and the uAPI in another one.
> > Feel free to pick up the patches as you see fit.
> > (The mptcp changes already go through their tree, so need to be
dropped here)
> > I can also resubmit the patches differently if preferred.
> 
> The selftests are just a canary in the coalmine. If we break a bunch of
> selftests chances are we'll also break compilation of real applications
> for people. Subjective, but I don't see a sufficient upside here to do
> that.
Okay. We'll have around this inconsistency then.
> FWIW the typelimits change broke compilation of ethtool, we'll see if
> anyone "outside kernel community itself" complains.
Can you point me to that breakage? I was unable to find it.


Thomas

On Tue, 3 Feb 2026 12:42:22 +0100 Thomas Wei?schuh
wrote:
> > FWIW the typelimits change broke compilation of ethtool, we'll see
if
> > anyone "outside kernel community itself" complains.  
> 
> Can you point me to that breakage? I was unable to find it.
Not reported on the ML, and it's kinda annoying to repro because 
the uAPI header sync script isn't committed :/ You have to check 
this out

 https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/

and run a script like this to sync headers from the kernel (then build):

#!/bin/bash -e

sn="${0##*/}"
export ARCH="x86_64"

if [ ! -d "$LINUX_GIT" ]; then
    echo "${sn}: LINUX_GIT not set" >&2
    exit 1
fi

pushd "$LINUX_GIT"
if [ -n "$1" ]; then
    git checkout "$1"
fi
desc=$(git describe --exact-match 2>/dev/null \
       || git show -s --abbrev=12 --pretty='commit %h')
kobj=$(mktemp -d)
make -j16 O="$kobj" allmodconfig
make -j16 O="$kobj" prepare
make -j16 O="$kobj" INSTALL_HDR_PATH="${kobj}/hdr"
headers_install
popd

pushd uapi
find . -type f -name '*.h' -exec cp -v
"${kobj}/hdr/include/{}" {} \;
popd
rm -rf "$kobj"

git add uapi
git commit -s -F - <<EOT
update UAPI header copies

Update to kernel ${desc}.

EOT