On Tue, Mar 08, 2022 at 02:38:47PM +0000, Andrew Cooper wrote:
> On 02/03/2022 14:27, Roger Pau Monne wrote:
> > 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_${name}_compile.log" ||
> > die
> > - sed -i 's/CFLAGS += -nostdinc -ffunction-sections
> > -fdata-sections/CFLAGS += -nostdinc/' Rules.mk
> > - mv -f arch/x86/Makefile.bak arch/x86/Makefile
> > + if grep -q 'nostdinc' Rules.mk; then
> > + # Support for old build system, attempt to set
> > -f{function,data}-sections and rebuild
> > + sed -i 's/CFLAGS += -nostdinc/CFLAGS += -nostdinc
> > -ffunction-sections -fdata-sections/' Rules.mk
> > + cp -p arch/x86/Makefile arch/x86/Makefile.bak
> > + sed -i
> > 's/--section-alignment=0x200000/--section-alignment=0x1000/'
> > arch/x86/Makefile
> > + # Restore timestamps to prevent spurious rebuilding
> > + touch --reference=arch/x86/Makefile.bak arch/x86/Makefile
> > + make "-j$CPUS" $XEN_DEBUG &> "${OUTPUT}/build_${name}_compile.log"
> > || die
> > + sed -i 's/CFLAGS += -nostdinc -ffunction-sections
> > -fdata-sections/CFLAGS += -nostdinc/' Rules.mk
> > + mv -f arch/x86/Makefile.bak arch/x86/Makefile
> > + else
> > + # -f{function,data}-sections set by CONFIG_LIVEPATCH
> > + make "-j$CPUS" $XEN_DEBUG &> "${OUTPUT}/build_${name}_compile.log"
> > || die
> > + fi
>
> This really ought to be the other way around, by spotting the thing we
> know is good, and then falling back to the heuristics. In light of the
> updates to the Xen side, something like:
I'm not sure I agree. I do prefer to spot the 'bad' one, and just
fallback to expecting Xen to correctly set -f{function,data}-sections
otherwise.
> if grep -q CC_SPLIT_SECTIONS Kconfig; then
Because this logic ties us to not moving CC_SPLIT_SECTIONS from being
defined in xen/Kconfig (or even changing it's name), and gain ties the
livepatch tools to internal details about the Xen build system.
Thanks, Roger.
