| Message ID | 20190128222106.19100-1-paul.burton@mips.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 0648e50e548d881d025b9419a1a168753c8e2bf7 |
| Headers | show |
| Series | MIPS: VDSO: Use same -m%-float cflag as the kernel proper | expand |
Paul Burton <paul.burton@mips.com> writes: > The MIPS VDSO build currently doesn't provide the -msoft-float flag to > the compiler as the kernel proper does. This results in an attempt to > use the compiler's default floating point configuration, which can be > problematic in cases where this is incompatible with the target CPU's > -march= flag. For example decstation_defconfig fails to build using > toolchains in which gcc was configured --with-fp-32=xx with the > following error: > > LDS arch/mips/vdso/vdso.lds > cc1: error: '-march=r3000' requires '-mfp32' > make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1 > > The kernel proper avoids this error because we build with the > -msoft-float compiler flag, rather than using the compiler's default. > Pass this flag through to the VDSO build so that it too becomes agnostic > to the toolchain's floating point configuration. > > Note that this is filtered out from KBUILD_CFLAGS rather than simply > always using -msoft-float such that if we switch the kernel to use > -mno-float in the future the VDSO will automatically inherit the change. > > The VDSO doesn't actually include any floating point code, and its > .MIPS.abiflags section is already manually generated to specify that > it's compatible with any floating point ABI. As such this change should > have no effect on the resulting VDSO, apart from fixing the build > failure for affected toolchains. > > Signed-off-by: Paul Burton <paul.burton@mips.com> > Reported-by: Kevin Hilman <khilman@baylibre.com> > Reported-by: Guenter Roeck <linux@roeck-us.net> > Cc: Maciej W. Rozycki <macro@linux-mips.org> > References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.nets/ > References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/ Tested-by: Kevin Hilman <khilman@baylibre.com>
Hello, Paul Burton wrote: > The MIPS VDSO build currently doesn't provide the -msoft-float flag to > the compiler as the kernel proper does. This results in an attempt to > use the compiler's default floating point configuration, which can be > problematic in cases where this is incompatible with the target CPU's > -march= flag. For example decstation_defconfig fails to build using > toolchains in which gcc was configured --with-fp-32=xx with the > following error: > > LDS arch/mips/vdso/vdso.lds > cc1: error: '-march=r3000' requires '-mfp32' > make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1 > > The kernel proper avoids this error because we build with the > -msoft-float compiler flag, rather than using the compiler's default. > Pass this flag through to the VDSO build so that it too becomes agnostic > to the toolchain's floating point configuration. > > Note that this is filtered out from KBUILD_CFLAGS rather than simply > always using -msoft-float such that if we switch the kernel to use > -mno-float in the future the VDSO will automatically inherit the change. > > The VDSO doesn't actually include any floating point code, and its > .MIPS.abiflags section is already manually generated to specify that > it's compatible with any floating point ABI. As such this change should > have no effect on the resulting VDSO, apart from fixing the build > failure for affected toolchains. > > Signed-off-by: Paul Burton <paul.burton@mips.com> > Reported-by: Kevin Hilman <khilman@baylibre.com> > Reported-by: Guenter Roeck <linux@roeck-us.net> > Cc: Maciej W. Rozycki <macro@linux-mips.org> > References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.net/ > References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/ Applied to mips-fixes. Thanks, Paul [ This message was auto-generated; if you believe anything is incorrect then please email paul.burton@mips.com to report it. ]
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile index f6fd340e39c2..314949b2261d 100644 --- a/arch/mips/vdso/Makefile +++ b/arch/mips/vdso/Makefile @@ -8,6 +8,7 @@ ccflags-vdso := \ $(filter -E%,$(KBUILD_CFLAGS)) \ $(filter -mmicromips,$(KBUILD_CFLAGS)) \ $(filter -march=%,$(KBUILD_CFLAGS)) \ + $(filter -m%-float,$(KBUILD_CFLAGS)) \ -D__VDSO__ ifdef CONFIG_CC_IS_CLANG
The MIPS VDSO build currently doesn't provide the -msoft-float flag to the compiler as the kernel proper does. This results in an attempt to use the compiler's default floating point configuration, which can be problematic in cases where this is incompatible with the target CPU's -march= flag. For example decstation_defconfig fails to build using toolchains in which gcc was configured --with-fp-32=xx with the following error: LDS arch/mips/vdso/vdso.lds cc1: error: '-march=r3000' requires '-mfp32' make[2]: *** [scripts/Makefile.build:379: arch/mips/vdso/vdso.lds] Error 1 The kernel proper avoids this error because we build with the -msoft-float compiler flag, rather than using the compiler's default. Pass this flag through to the VDSO build so that it too becomes agnostic to the toolchain's floating point configuration. Note that this is filtered out from KBUILD_CFLAGS rather than simply always using -msoft-float such that if we switch the kernel to use -mno-float in the future the VDSO will automatically inherit the change. The VDSO doesn't actually include any floating point code, and its .MIPS.abiflags section is already manually generated to specify that it's compatible with any floating point ABI. As such this change should have no effect on the resulting VDSO, apart from fixing the build failure for affected toolchains. Signed-off-by: Paul Burton <paul.burton@mips.com> Reported-by: Kevin Hilman <khilman@baylibre.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Cc: Maciej W. Rozycki <macro@linux-mips.org> References: https://lore.kernel.org/linux-mips/1477843551-21813-1-git-send-email-linux@roeck-us.net/ References: https://kernelci.org/build/id/5c4e4ae059b5142a249ad004/logs/ --- arch/mips/vdso/Makefile | 1 + 1 file changed, 1 insertion(+)