[PATCH 2/3] gcc: set the default target arch


Dan McGregor
 

From: Daniel McGregor <daniel.mcgregor@...>

The default x86-64 architecture for target gcc (ie, the one in poky
build appliances) is native. Since we have a variety of build systems
it will occasionally produce instructions that don't work on all of
our development system.

Instead, set gcc's default architecture to the one specified in
TUNE_CC_ARCH, that guarantees that gcc-runtime and any binaries
produced are compatible with the target machine type.

Signed-off-by: Daniel McGregor <daniel.mcgregor@...>
---
meta/recipes-devtools/gcc/gcc-common.inc | 10 ++++++++++
meta/recipes-devtools/gcc/gcc-target.inc | 2 +-
2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/meta/recipes-devtools/gcc/gcc-common.inc b/meta/recipes-devtools/gcc/gcc-common.inc
index 2abc0e355d7..d3b36937bf4 100644
--- a/meta/recipes-devtools/gcc/gcc-common.inc
+++ b/meta/recipes-devtools/gcc/gcc-common.inc
@@ -32,6 +32,16 @@ def get_gcc_float_setting(bb, d):

get_gcc_float_setting[vardepvalue] = "${@get_gcc_float_setting(bb, d)}"

+def get_gcc_x86_64_arch_setting(bb, d):
+ import re
+ march = re.match(r'^.*-march=([^\s]*)', d.getVar('TUNE_CCARGS'))
+ if march:
+ return "--with-arch=%s " % march.group(1)
+ # The earliest supported x86-64 CPU
+ return "--with-arch=core2"
+
+get_gcc_x86_64_arch_setting[vardepvalue] = "${@get_gcc_x86_64_arch_setting(bb, d)}"
+
def get_gcc_mips_plt_setting(bb, d):
if d.getVar('TRANSLATED_TARGET_ARCH') in [ 'mips', 'mipsel' ] and bb.utils.contains('DISTRO_FEATURES', 'mplt', True, False, d):
return "--with-mips-plt"
diff --git a/meta/recipes-devtools/gcc/gcc-target.inc b/meta/recipes-devtools/gcc/gcc-target.inc
index cc65e995c30..7dac3ef422c 100644
--- a/meta/recipes-devtools/gcc/gcc-target.inc
+++ b/meta/recipes-devtools/gcc/gcc-target.inc
@@ -19,7 +19,7 @@ EXTRA_OECONF:append:armv6:class-target = " --with-arch=armv6${ARMFPARCHEXT}"
EXTRA_OECONF:append:armv7a:class-target = " --with-arch=armv7-a${ARMFPARCHEXT}"
EXTRA_OECONF:append:armv7ve:class-target = " --with-arch=armv7ve${ARMFPARCHEXT}"
EXTRA_OECONF:append:arc:class-target = " --with-cpu=${TUNE_PKGARCH}"
-EXTRA_OECONF:append:x86-64:class-target = " --with-arch=native"
+EXTRA_OECONF:append:x86-64:class-target = " ${@get_gcc_x86_64_arch_setting(bb, d)}"

# libcc1 requres gcc_cv_objdump when cross build, but gcc_cv_objdump is
# set in subdir gcc, so subdir libcc1 can't use it, export it here to
--
2.37.3


Ross Burton
 

On 28 Sep 2022, at 23:13, Dan McGregor via lists.openembedded.org <danismostlikely=gmail.com@...> wrote:

From: Daniel McGregor <daniel.mcgregor@...>

The default x86-64 architecture for target gcc (ie, the one in poky
build appliances) is native. Since we have a variety of build systems
it will occasionally produce instructions that don't work on all of
our development system.

Instead, set gcc's default architecture to the one specified in
TUNE_CC_ARCH, that guarantees that gcc-runtime and any binaries
produced are compatible with the target machine type.
Can you explain the use-case here? These are target binaries, so why is the development system relevant?

Ross


Ross Burton
 

On 29 Sep 2022, at 16:31, Daniel McGregor <daniel.mcgregor@...> wrote:

Sure, I'm actually talking about host binaries, built inside our equivalent of a poky build appliance. The most obvious example is pseudo-native built on our newest build servers. GCC decides to use instructions (in particular BMI2 instructions) that don't exist on our older build machines. Since we use a common shared state and uninative it was becoming pretty common for old machines to pull shared state built on a much newer one, leading to build failures do to invalid opcode exceptions.
Ah, so you build a container with Yocto and then do your Yocto builds inside that container. Got it, thanks.

Ross