From: Daniel P. Berrangé Date: Thu, 8 Jan 2026 14:14:07 +0000 (+0000) Subject: meson: disable libatomic with GCC >= 16 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=365a2248ae69f306fe7997fd966bcb1c16a08695;p=thirdparty%2Fqemu.git meson: disable libatomic with GCC >= 16 Historically it was required to ask for libatomic explicitly with -latomic, but with GCC >= 16 apps will get linked to libatomic whether they ask for it or not. This invalidates QEMU's check for atomic op support for int128 which explicitly does NOT want to use the libatomic impl. As a result with GCC >= 16, QEMU is now getting linked to libatomic and is activating CONFIG_ATOMIC128. This in turn exposes a bug in GCC's libatomic.a static buld which is incompatible with the use of -static-pie leading to build failures like: /usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/16/libatomic.a(cas_16_.o): relocation R_X86_64_32 against hidden symbol `libat_compare_exchange_16_i1' can not be used when making a PIE object /usr/bin/ld: failed to set dynamic section sizes: bad value collect2: error: ld returned 1 exit status The newly introduced -fno-link-libatomic flag can be used to disable the new automatic linking of libatomic. Setting this in qemu_isa_flags early on ensures that the check for CONFIG_ATOMIC128 still works correctly. Signed-off-by: Daniel P. Berrangé Acked-by: Paolo Bonzini Reviewed-by: Richard Henderson Signed-off-by: Richard Henderson Message-ID: <20260108141407.2151817-1-berrange@redhat.com> --- diff --git a/meson.build b/meson.build index db87358d62..56df08c10e 100644 --- a/meson.build +++ b/meson.build @@ -445,6 +445,15 @@ if host_arch in ['i386', 'x86_64'] endif endif +# GCC >= 16 automatically tries to link libatomic for all programs. +# +# QEMU explicitly does NOT want to use libatomic for int128 types. +# +# Later checks assume we won't get atomic ops for int128 without +# explicitly asking for -latomic, so we must disable GCC's new +# automatic linking with the new -fno-link-libatomic flag +qemu_isa_flags += cc.get_supported_arguments('-fno-link-libatomic') + qemu_common_flags = qemu_isa_flags + qemu_common_flags if get_option('prefer_static')