On 7/26/23 01:23, Nathan Chancellor wrote:
Hi Mingzheng,
Thanks for the patch!
On Wed, Jul 26, 2023 at 01:04:05AM +0800, Mingzheng Xing wrote:
When compiling the kernel with the toolchain composed of GCC >= 12.1.0 and
binutils < 2.38, default ISA spec used when building binutils and GCC, the
following build failure will appear because the
CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI is not turned on.
(i.e, gcc-12.1.0 and binutils-2.36, or gcc-12.3.0 and binutils-2.37, use
default ISA spec.)
CC arch/riscv/kernel/vdso/vgettimeofday.o
<<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h: Assembler messages:
<<BUILDDIR>>/arch/riscv/include/asm/vdso/gettimeofday.h:79: Error: unrecognized opcode `csrr a5,0xc01'
The gift that keeps on giving :/
Yeah, but things will get better :)
Binutils has updated the default ISA spec version, and the community has
responded well to this[1][2][3], but it appears that this is not over yet.
We also need to consider the situation of binutils < 2.38 but
GCC >= 12.1.0, since the combination between different versions of GCC and
binutils is not unique, which is to some extent flexible. GCC release
12.1.0 updated the default ISA spec version in GCC commit[4].
I suspect this combination is not too common because binutils 2.38 came
out before GCC 12.1.0 but as you note, it is obviously possible. What
toolchain has this combination in the wild, which would be helpful for
documentation purposes?
Actually, this issue was discovered during the upgrade of the distribution
openEuler for RISC-V. It is a temporary phenomenon caused by
inconsistent upgrade speeds of packages such as GCC and binutils.
From my limited understanding, GCC and binutils are not strictly
version-bound in some other distributions, so I can't rule out this issue
happening in other scenarios. But once it happens it can cause problems
with compiling the kernel.
For more information, please refer to:
commit 6df2a016c0c8 ("riscv: fix build with binutils 2.38")
commit e89c2e815e76 ("riscv: Handle zicsr/zifencei issues between clang and binutils")
[1]:https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/aE1ZeHHCYf4
[2]:https://lore.kernel.org/all/20230308220842.1231003-1-conor@xxxxxxxxxx
[3]:https://lore.kernel.org/all/20230223220546.52879-1-conor@xxxxxxxxxx
[4]:https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
Signed-off-by: Mingzheng Xing<xingmingzheng@xxxxxxxxxxx>
---
arch/riscv/Kconfig | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 4c07b9189c86..b49cea30f6cc 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -570,11 +570,15 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
def_bool y
#https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
- depends on AS_IS_GNU && AS_VERSION >= 23800
+ #https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=98416dbb0a62579d4a7a4a76bab51b5b52fec2cd
+ depends on CC_IS_GCC && GCC_VERSION >= 120100 || \
+ AS_IS_GNU && AS_VERSION >= 23800
GCC_VERSION will be 0 for clang, so you don't need the CC_IS_GCC check.
With that change, this should be able to stay on one line:
depends on GCC_VERSION >= 120100 || (AS_IS_GNU && AS_VERSION >= 23800)
OK, I'll change it in v2.
Thanks,
Mingzheng.
help
Newer binutils versions default to ISA spec version 20191213 which
moves some instructions from the I extension to the Zicsr and Zifencei
extensions.
+ Similarly, GCC release 12.1.0 has changed the default ISA spec version to
+ 20191213, so the above situation requires this option to be enabled.
config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
def_bool y
--
2.34.1
Cheers,
Nathan
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