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commit: 02aa6328a720c86d0157c4582f7e5bac72ae9296 |
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Author: James Le Cuirot <chewi <AT> gentoo <DOT> org> |
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AuthorDate: Sat Jun 11 21:11:12 2022 +0000 |
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Commit: Sam James <sam <AT> gentoo <DOT> org> |
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CommitDate: Sat Jun 25 21:39:28 2022 +0000 |
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URL: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=02aa6328 |
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|
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sys-libs/glibc: Add stack-realign flag for compat with old 32-bit x86 binaries |
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|
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Older 32-bit x86 binaries aligned the stack to 4 bytes, whereas modern |
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binaries align to 16 bytes. These older binaries sometimes segfault when |
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newer libraries use SSE instructions. This is becoming increasingly |
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common. Applying the -mstackrealign flag to the 32-bit build works |
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around the issue but at a performance cost. Other popular |
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distributions always apply this. |
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|
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[sam: There's no good choices here. As Ionen pointed out (I'd missed |
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any reports of this), this ends up getting worse with GCC 12's |
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default-on vectorisation at -O2. Let's make it optional for now for |
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32-bit/x86 (irrelevant for other arches, it's specific to x86 ABI). |
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|
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ncurses is going to need similar treatment. If we end up having |
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to do this for far more packages, we may revisit and e.g. |
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just append-flags in ebuilds for right ABI and tell users |
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to set -mno-stackrealign, or similar. |
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|
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Another option would be to set this globally by default (again, |
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this is only ever for x86), but it'd possibly be a big performance |
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hit (and bad enough doing it in glibc, but it's unavoidable). |
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|
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The only saving grace here is that there aren't _that_ many |
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libraries with such longevity & ABI stability from back then |
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that older applications are using.] |
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|
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Bug: https://bugs.gentoo.org/616402 |
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Bug: https://github.com/taviso/123elf/issues/12 |
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Signed-off-by: James Le Cuirot <chewi <AT> gentoo.org> |
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Closes: https://github.com/gentoo/gentoo/pull/25858 |
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Signed-off-by: Sam James <sam <AT> gentoo.org> |
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|
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sys-libs/glibc/glibc-2.35-r7.ebuild | 31 ++++++++++++++++++------------- |
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sys-libs/glibc/glibc-9999.ebuild | 31 ++++++++++++++++++------------- |
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sys-libs/glibc/metadata.xml | 1 + |
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3 files changed, 37 insertions(+), 26 deletions(-) |
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|
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diff --git a/sys-libs/glibc/glibc-2.35-r7.ebuild b/sys-libs/glibc/glibc-2.35-r7.ebuild |
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index a9b4a0d16717..3e8358532526 100644 |
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--- a/sys-libs/glibc/glibc-2.35-r7.ebuild |
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+++ b/sys-libs/glibc/glibc-2.35-r7.ebuild |
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@@ -44,7 +44,7 @@ SRC_URI+=" https://gitweb.gentoo.org/proj/locale-gen.git/snapshot/locale-gen-${L |
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SRC_URI+=" multilib-bootstrap? ( https://dev.gentoo.org/~dilfridge/distfiles/gcc-multilib-bootstrap-${GCC_BOOTSTRAP_VER}.tar.xz )" |
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SRC_URI+=" systemd? ( https://gitweb.gentoo.org/proj/toolchain/glibc-systemd.git/snapshot/glibc-systemd-${GLIBC_SYSTEMD_VER}.tar.gz )" |
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|
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-IUSE="audit caps cet +clone3 compile-locales +crypt custom-cflags doc experimental-loong gd headers-only +multiarch multilib multilib-bootstrap nscd profile selinux +ssp +static-libs suid systemd systemtap test vanilla" |
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+IUSE="audit caps cet +clone3 compile-locales +crypt custom-cflags doc experimental-loong gd headers-only +multiarch multilib multilib-bootstrap nscd profile selinux +ssp stack-realign +static-libs suid systemd systemtap test vanilla" |
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|
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# Minimum kernel version that glibc requires |
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MIN_KERN_VER="3.2.0" |
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@@ -305,22 +305,27 @@ setup_target_flags() { |
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export CFLAGS="-march=${t} ${CFLAGS}" |
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einfo "Auto adding -march=${t} to CFLAGS #185404" |
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fi |
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+ # For compatibility with older binaries at slight performance cost. |
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+ use stack-realign && export CFLAGS+=" -mstackrealign" |
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;; |
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amd64) |
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# -march needed for #185404 #199334 |
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# TODO: See cross-compile issues listed above for x86. |
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- [[ ${ABI} == x86 ]] && |
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- if ! do_compile_test "${CFLAGS_x86}" 'void f(int i, void *p) {if (__sync_fetch_and_add(&i, 1)) f(i, p);}\nint main(){return 0;}\n'; then |
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- local t=${CTARGET_OPT:-${CTARGET}} |
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- t=${t%%-*} |
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- # Normally the target is x86_64-xxx, so turn that into the -march that |
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- # gcc actually accepts. #528708 |
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- [[ ${t} == "x86_64" ]] && t="x86-64" |
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- filter-flags '-march=*' |
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- # ugly, ugly, ugly. ugly. |
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- CFLAGS_x86=$(CFLAGS=${CFLAGS_x86} filter-flags '-march=*'; echo "${CFLAGS}") |
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- export CFLAGS_x86="${CFLAGS_x86} -march=${t}" |
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- einfo "Auto adding -march=${t} to CFLAGS_x86 #185404 (ABI=${ABI})" |
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+ if [[ ${ABI} == x86 ]]; then |
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+ if ! do_compile_test "${CFLAGS_x86}" 'void f(int i, void *p) {if (__sync_fetch_and_add(&i, 1)) f(i, p);}\nint main(){return 0;}\n'; then |
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+ local t=${CTARGET_OPT:-${CTARGET}} |
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+ t=${t%%-*} |
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+ # Normally the target is x86_64-xxx, so turn that into the -march that |
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+ # gcc actually accepts. #528708 |
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+ [[ ${t} == "x86_64" ]] && t="x86-64" |
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+ filter-flags '-march=*' |
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+ # ugly, ugly, ugly. ugly. |
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+ CFLAGS_x86=$(CFLAGS=${CFLAGS_x86} filter-flags '-march=*'; echo "${CFLAGS}") |
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+ export CFLAGS_x86="${CFLAGS_x86} -march=${t}" |
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+ einfo "Auto adding -march=${t} to CFLAGS_x86 #185404 (ABI=${ABI})" |
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+ fi |
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+ # For compatibility with older binaries at slight performance cost. |
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+ use stack-realign && export CFLAGS_x86+=" -mstackrealign" |
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fi |
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;; |
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mips) |
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|
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diff --git a/sys-libs/glibc/glibc-9999.ebuild b/sys-libs/glibc/glibc-9999.ebuild |
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index 2a030e2f9928..b35b2febd192 100644 |
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--- a/sys-libs/glibc/glibc-9999.ebuild |
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+++ b/sys-libs/glibc/glibc-9999.ebuild |
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@@ -44,7 +44,7 @@ SRC_URI+=" https://gitweb.gentoo.org/proj/locale-gen.git/snapshot/locale-gen-${L |
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SRC_URI+=" multilib-bootstrap? ( https://dev.gentoo.org/~dilfridge/distfiles/gcc-multilib-bootstrap-${GCC_BOOTSTRAP_VER}.tar.xz )" |
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SRC_URI+=" systemd? ( https://gitweb.gentoo.org/proj/toolchain/glibc-systemd.git/snapshot/glibc-systemd-${GLIBC_SYSTEMD_VER}.tar.gz )" |
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|
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-IUSE="audit caps cet compile-locales +crypt custom-cflags doc gd headers-only +multiarch multilib multilib-bootstrap nscd profile selinux +ssp +static-libs suid systemd systemtap test vanilla" |
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+IUSE="audit caps cet compile-locales +crypt custom-cflags doc gd headers-only +multiarch multilib multilib-bootstrap nscd profile selinux +ssp stack-realign +static-libs suid systemd systemtap test vanilla" |
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|
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# Minimum kernel version that glibc requires |
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MIN_KERN_VER="3.2.0" |
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@@ -305,22 +305,27 @@ setup_target_flags() { |
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export CFLAGS="-march=${t} ${CFLAGS}" |
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einfo "Auto adding -march=${t} to CFLAGS #185404" |
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fi |
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+ # For compatibility with older binaries at slight performance cost. |
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+ use stack-realign && export CFLAGS+=" -mstackrealign" |
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;; |
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amd64) |
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# -march needed for #185404 #199334 |
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# TODO: See cross-compile issues listed above for x86. |
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- [[ ${ABI} == x86 ]] && |
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- if ! do_compile_test "${CFLAGS_x86}" 'void f(int i, void *p) {if (__sync_fetch_and_add(&i, 1)) f(i, p);}\nint main(){return 0;}\n'; then |
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- local t=${CTARGET_OPT:-${CTARGET}} |
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- t=${t%%-*} |
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- # Normally the target is x86_64-xxx, so turn that into the -march that |
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- # gcc actually accepts. #528708 |
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- [[ ${t} == "x86_64" ]] && t="x86-64" |
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- filter-flags '-march=*' |
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- # ugly, ugly, ugly. ugly. |
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- CFLAGS_x86=$(CFLAGS=${CFLAGS_x86} filter-flags '-march=*'; echo "${CFLAGS}") |
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- export CFLAGS_x86="${CFLAGS_x86} -march=${t}" |
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- einfo "Auto adding -march=${t} to CFLAGS_x86 #185404 (ABI=${ABI})" |
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+ if [[ ${ABI} == x86 ]]; then |
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+ if ! do_compile_test "${CFLAGS_x86}" 'void f(int i, void *p) {if (__sync_fetch_and_add(&i, 1)) f(i, p);}\nint main(){return 0;}\n'; then |
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+ local t=${CTARGET_OPT:-${CTARGET}} |
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+ t=${t%%-*} |
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+ # Normally the target is x86_64-xxx, so turn that into the -march that |
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+ # gcc actually accepts. #528708 |
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+ [[ ${t} == "x86_64" ]] && t="x86-64" |
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+ filter-flags '-march=*' |
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+ # ugly, ugly, ugly. ugly. |
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+ CFLAGS_x86=$(CFLAGS=${CFLAGS_x86} filter-flags '-march=*'; echo "${CFLAGS}") |
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+ export CFLAGS_x86="${CFLAGS_x86} -march=${t}" |
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+ einfo "Auto adding -march=${t} to CFLAGS_x86 #185404 (ABI=${ABI})" |
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+ fi |
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+ # For compatibility with older binaries at slight performance cost. |
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+ use stack-realign && export CFLAGS_x86+=" -mstackrealign" |
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fi |
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;; |
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mips) |
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|
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diff --git a/sys-libs/glibc/metadata.xml b/sys-libs/glibc/metadata.xml |
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index e00a008ac5c3..bcaf604fa542 100644 |
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--- a/sys-libs/glibc/metadata.xml |
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+++ b/sys-libs/glibc/metadata.xml |
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@@ -17,6 +17,7 @@ |
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<flag name="multilib-bootstrap">Provide prebuilt libgcc.a and crt files if missing. Only needed for ABI switch.</flag> |
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<flag name="nscd">Build, and enable support for, the Name Service Cache Daemon</flag> |
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<flag name="ssp">protect stack of glibc internals</flag> |
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+ <flag name="stack-realign">Realign the stack in the 32-bit build for compatibility with older binaries at slight performance cost</flag> |
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<flag name="static-pie">Enable static PIE support (runtime files for -static-pie gcc option).</flag> |
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<flag name="suid">Make internal pt_chown helper setuid -- not needed if using Linux and have /dev/pts mounted with gid=5</flag> |
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<flag name="systemtap">enable systemtap static probe points</flag> |
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