RISC-V 64bit and 32bit binaries on the same system
Andreas K. Hüttel
dilfridge@gentoo.org
Mon Sep 7 13:32:39 GMT 2020
Hi all,
as you probably know, the gcc multilib settings for riscv build and install 4
ABI (rv64/lp64d, rv64/lp64, rv32/ilp32d, rv32/ilp32). Now that rv32 support is
in glibc, I gave this a try (*) in qemu-user.
gcc and glibc build and install fine. However, there's a fundamental problem
with this configuration. ld.so does not filter by ELFCLASS (as it does, e.g.,
for x64-64 vs i686), and the order of directories in the dynamic linker config
determines e.g. which libstdc++ a binary sees first. [#]
Which means, either rv32 or rv64 binaries will terminate with a "wrong
ELFCLASS" fatal error.
Now, what to do?
* Introduce a special cache flag as for x86-64 FLAG_X8664_LIB64?
* Make ld.so ignore wrong-ELFCLASS binaries instead of producing an error?
(Same result handled at different point...)
* Propose to change the gcc multilib profiles so we don't pretend that this
works?
Cheers,
Andreas
(*) I know that there is no real hardware that can run both rv64 and rv32 at
the moment. However, it would be useful for me to bootstrap different single-
ABI environments.
[#]
(riscv-main chroot) farino /lib # ldconfig -p|grep c++
libstdc++.so.6 (libc6,double-float) => /usr/lib/gcc/riscv64-unknown-
linux-gnu/10.2.0/lib64/lp64d/libstdc++.so.6
libstdc++.so.6 (libc6,double-float) => /usr/lib/gcc/riscv64-unknown-
linux-gnu/10.2.0/lib32/ilp32d/libstdc++.so.6
libstdc++.so.6 (libc6,soft-float) => /usr/lib/gcc/riscv64-unknown-
linux-gnu/10.2.0/lib64/lp64/libstdc++.so.6
libstdc++.so.6 (libc6,soft-float) => /usr/lib/gcc/riscv64-unknown-
linux-gnu/10.2.0/lib32/ilp32/libstdc++.so.6
libstdc++.so (libc6,double-float) => /usr/lib/gcc/riscv64-unknown-
linux-gnu/10.2.0/lib64/lp64d/libstdc++.so
libstdc++.so (libc6,double-float) => /usr/lib/gcc/riscv64-unknown-
linux-gnu/10.2.0/lib32/ilp32d/libstdc++.so
libstdc++.so (libc6,soft-float) => /usr/lib/gcc/riscv64-unknown-linux-
gnu/10.2.0/lib64/lp64/libstdc++.so
libstdc++.so (libc6,soft-float) => /usr/lib/gcc/riscv64-unknown-linux-
gnu/10.2.0/lib32/ilp32/libstdc++.so
versus
farino ~ # ldconfig -p |grep c++
libstdc++.so.6 (libc6,x86-64) => /usr/lib/gcc/x86_64-pc-linux-gnu/
9.3.0/libstdc++.so.6
libstdc++.so.6 (libc6) => /usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/32/
libstdc++.so.6
libstdc++.so (libc6,x86-64) => /usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/
libstdc++.so
libstdc++.so (libc6) => /usr/lib/gcc/x86_64-pc-linux-gnu/9.3.0/32/
libstdc++.so
libnetcdf_c++.so.4 (libc6,x86-64) => /usr/lib64/libnetcdf_c++.so.4
libnetcdf_c++.so (libc6,x86-64) => /usr/lib64/libnetcdf_c++.so
--
Andreas K. Hüttel
dilfridge@gentoo.org
Gentoo Linux developer
(council, qa, toolchain, base-system, perl, libreoffice)
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