On Wed, Mar 02, 2022 at 04:41:36PM +0100, Doebel, Bjoern wrote:
> On 02.03.22 15:27, Roger Pau Monne wrote:
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> >
> >
> > Do not attempt to modify the build system if CFLAGS are not set in
> > Rules.mk, and instead rely on CONFIG_LIVEPATCH already setting
> > -f{function,data}-sections.
> >
> > Signed-off-by: Roger Pau Monné <[email protected]>
> > ---
> > This depends on getting the patch to add -f{function,data}-sections
> > when using CONFIG_LIVEPATCH accepted.
> > ---
> > livepatch-build | 22 ++++++++++++++--------
> > 1 file changed, 14 insertions(+), 8 deletions(-)
> >
> > diff --git a/livepatch-build b/livepatch-build
> > index 38a92be..656cdac 100755
> > --- a/livepatch-build
> > +++ b/livepatch-build
> > @@ -98,14 +98,20 @@ function build_special()
> >
> > # Build with special GCC flags
> > cd "${SRCDIR}/xen" || die
> > - sed -i 's/CFLAGS += -nostdinc/CFLAGS += -nostdinc -ffunction-sections
> > -fdata-sections/' Rules.mk
> > - cp -p arch/x86/Makefile arch/x86/Makefile.bak
> > - sed -i 's/--section-alignment=0x200000/--section-alignment=0x1000/'
> > arch/x86/Makefile
> > - # Restore timestamps to prevent spurious rebuilding
> > - touch --reference=arch/x86/Makefile.bak arch/x86/Makefile
> > - make "-j$CPUS" $XEN_DEBUG &> "${OUTPUT}/build_${name}_compile.log" ||
> > die
> > - sed -i 's/CFLAGS += -nostdinc -ffunction-sections
> > -fdata-sections/CFLAGS += -nostdinc/' Rules.mk
> > - mv -f arch/x86/Makefile.bak arch/x86/Makefile
> > + if grep -q 'nostdinc' Rules.mk; then
>
> This means we are still breaking livepatch builds for all Xen versions
> between your recent patch and the original patch that moved CFLAGS to
> xen/Makefile (commit 2740d96efdd3009f8adb40aacdbcf05cfe8d1bbb, Fri Apr 24
> 14:57:10 2020 +0200).
>
> Is this acceptable? (I mean, no one seems to have noticed...)
I've also wondered. I think a reasonable approach would be for
interested parties (ie: using livepatch) to backport the commit that
sets -f{function,data}-sections in their Xen build for that broken
window.
I think we could also consider it as a candidate for backport to
stable branches, but that won't fix versions we have already
shipped.
Thanks, Roger.
