| Message ID | 20190625210441.199514-1-ndesaulniers@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | ARM: Kconfig: default to AEABI w/ Clang | expand |
On Tue, Jun 25, 2019 at 11:04 PM 'Nick Desaulniers' via Clang Built Linux <clang-built-linux@googlegroups.com> wrote: > > Clang produces references to __aeabi_uidivmod and __aeabi_idivmod for > arm-linux-gnueabi and arm-linux-gnueabihf targets incorrectly when AEABI > is not selected (such as when OABI_COMPAT is selected). > > While this means that OABI userspaces wont be able to upgraded to > kernels built with Clang, it means that boards that don't enable AEABI > like s3c2410_defconfig will stop failing to link in KernelCI when built > with Clang. > > Link: https://github.com/ClangBuiltLinux/linux/issues/482 > Link: https://groups.google.com/forum/#!msg/clang-built-linux/yydsAAux5hk/GxjqJSW-AQAJ > Suggested-by: Arnd Bergmann <arnd@arndb.de> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Looks good to me, Reviewed-by: Arnd Bergmann <arnd@arndb.de> Please add it to Russell's patch tracker if you haven't already. Most of the .config files that don't set AEABI (and a lot of the others as well) have likely never been booted on real hardware with a modern kernel in a long time. There have not been any distros using OABI in a long time (Debian Lenny was released in 2009), and gcc dropped support for it a few years later. We could probably change most of these to use OABI_COMPAT instead, aside from any ones that Russell wants to keep building as OABI for his own machines. Arnd
On Tue, Jun 25, 2019 at 11:04 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > Clang produces references to __aeabi_uidivmod and __aeabi_idivmod for > arm-linux-gnueabi and arm-linux-gnueabihf targets incorrectly when AEABI > is not selected (such as when OABI_COMPAT is selected). > > While this means that OABI userspaces wont be able to upgraded to > kernels built with Clang, it means that boards that don't enable AEABI > like s3c2410_defconfig will stop failing to link in KernelCI when built > with Clang. > > Link: https://github.com/ClangBuiltLinux/linux/issues/482 > Link: https://groups.google.com/forum/#!msg/clang-built-linux/yydsAAux5hk/GxjqJSW-AQAJ > Suggested-by: Arnd Bergmann <arnd@arndb.de> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> As reflecting the state of things with CLANG it's: Reviewed-by: Linus Walleij <linus.walleij@linaro.org> But I think we in general need to have some discussion on how to proceed with OABI userspaces. I am well aware of distributions like OpenWrt using EABI even on ARMv4 with "tricks" like this: https://github.com/openwrt/openwrt/blob/master/toolchain/gcc/patches/9.1.0/840-armv4_pass_fix-v4bx_to_ld.patch I have one OABI that I can think of would be nice to live on and it's the RedHat derivative on my Foorbridge NetWinder. OK I wouldn't cry if we have to kill it because it is too hard to keep supporting it, but it has been running the latest kernels all along so if it's not a huge effort I'd be interested in knowing the options. Yours, Linus Walleij
On Thu, Jul 4, 2019 at 10:13 AM Linus Walleij <linus.walleij@linaro.org> wrote: > On Tue, Jun 25, 2019 at 11:04 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > > Clang produces references to __aeabi_uidivmod and __aeabi_idivmod for > > arm-linux-gnueabi and arm-linux-gnueabihf targets incorrectly when AEABI > > is not selected (such as when OABI_COMPAT is selected). > > > > While this means that OABI userspaces wont be able to upgraded to > > kernels built with Clang, it means that boards that don't enable AEABI > > like s3c2410_defconfig will stop failing to link in KernelCI when built > > with Clang. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/482 > > Link: https://groups.google.com/forum/#!msg/clang-built-linux/yydsAAux5hk/GxjqJSW-AQAJ > > Suggested-by: Arnd Bergmann <arnd@arndb.de> > > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > > As reflecting the state of things with CLANG it's: > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > But I think we in general need to have some discussion on how to > proceed with OABI userspaces. > > I am well aware of distributions like OpenWrt using EABI even > on ARMv4 with "tricks" like this: > https://github.com/openwrt/openwrt/blob/master/toolchain/gcc/patches/9.1.0/840-armv4_pass_fix-v4bx_to_ld.patch I did not expect that to be necessary in gcc as long as it supports building for armv4 (non-t), but I might be missing something here. > I have one OABI that I can think of would be nice to live on > and it's the RedHat derivative on my Foorbridge NetWinder. > OK I wouldn't cry if we have to kill it because it is too hard to > keep supporting it, but it has been running the latest kernels > all along so if it's not a huge effort I'd be interested in knowing > the options. But do you see any problems with cross-compiling kernels to EABI with CONFIG_OABI_COMPAT for machines like that? I would guess that you can't actually build modern kernels on the RedHat OABI compiler any more as they presumably predate the current minimum gcc-4.6. Arnd
On Thu, Jul 04, 2019 at 10:29:35AM +0200, Arnd Bergmann wrote: > On Thu, Jul 4, 2019 at 10:13 AM Linus Walleij <linus.walleij@linaro.org> wrote: > > On Tue, Jun 25, 2019 at 11:04 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > > > > Clang produces references to __aeabi_uidivmod and __aeabi_idivmod for > > > arm-linux-gnueabi and arm-linux-gnueabihf targets incorrectly when AEABI > > > is not selected (such as when OABI_COMPAT is selected). > > > > > > While this means that OABI userspaces wont be able to upgraded to > > > kernels built with Clang, it means that boards that don't enable AEABI > > > like s3c2410_defconfig will stop failing to link in KernelCI when built > > > with Clang. > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/482 > > > Link: https://groups.google.com/forum/#!msg/clang-built-linux/yydsAAux5hk/GxjqJSW-AQAJ > > > Suggested-by: Arnd Bergmann <arnd@arndb.de> > > > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> > > > > As reflecting the state of things with CLANG it's: > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > > > But I think we in general need to have some discussion on how to > > proceed with OABI userspaces. > > > > I am well aware of distributions like OpenWrt using EABI even > > on ARMv4 with "tricks" like this: > > https://github.com/openwrt/openwrt/blob/master/toolchain/gcc/patches/9.1.0/840-armv4_pass_fix-v4bx_to_ld.patch > > I did not expect that to be necessary in gcc as long as it supports > building for armv4 (non-t), but I might be missing something here. > > > I have one OABI that I can think of would be nice to live on > > and it's the RedHat derivative on my Foorbridge NetWinder. > > OK I wouldn't cry if we have to kill it because it is too hard to > > keep supporting it, but it has been running the latest kernels > > all along so if it's not a huge effort I'd be interested in knowing > > the options. > > But do you see any problems with cross-compiling kernels to > EABI with CONFIG_OABI_COMPAT for machines like that? Yes, there are a few ioctls that break. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 8869742a85df..3539be870055 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1545,8 +1545,9 @@ config ARM_PATCH_IDIV code to do integer division. config AEABI - bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && !CPU_V7M && !CPU_V6 && !CPU_V6K - default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K + bool "Use the ARM EABI to compile the kernel" if !CPU_V7 && \ + !CPU_V7M && !CPU_V6 && !CPU_V6K && !CC_IS_CLANG + default CPU_V7 || CPU_V7M || CPU_V6 || CPU_V6K || CC_IS_CLANG help This option allows for the kernel to be compiled using the latest ARM ABI (aka EABI). This is only useful if you are using a user
Clang produces references to __aeabi_uidivmod and __aeabi_idivmod for arm-linux-gnueabi and arm-linux-gnueabihf targets incorrectly when AEABI is not selected (such as when OABI_COMPAT is selected). While this means that OABI userspaces wont be able to upgraded to kernels built with Clang, it means that boards that don't enable AEABI like s3c2410_defconfig will stop failing to link in KernelCI when built with Clang. Link: https://github.com/ClangBuiltLinux/linux/issues/482 Link: https://groups.google.com/forum/#!msg/clang-built-linux/yydsAAux5hk/GxjqJSW-AQAJ Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- arch/arm/Kconfig | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) -- 2.22.0.410.gd8fdbe21b5-goog