Apologies if this is a duplicate. My first attempt to subscribe
failed, and my first attempt to send email apparently didn't work as I
don't see the message in the mailing list archive.
I was forwarded a complaint that the RISC-V ABI does not comply with
the FHS. The RISC-V ABI specifies 6 ABI variants at present, and they
are located in /lib32/ilp32, /lib32/ilp32f, /lib32/ilp32d,
/lib64/lp64, /lib64/lp64f, and /lib64/lp64d. These are for
32-bit/64-bit soft-float/float-only/float+double ABIs. We expect more
ABIs will be supported in the future to deal with more ISA variations.
The FHS says that libraries can only be in /lib<qual> but does not
clearly specify whether / is allowed in qual or not. Some insist that
this is implied. A more generous interpretation might allow <qual> to
contain a slash. It isn't clear if we are compliant or not. This
should be clarified.
If slash is not allowed in <qual> then we are not the only system that
is not compliant. Multiarch systems like Debian and Ubuntu put
libraries in /lib/<target-tuple> for instance. Though looking at
Debian docs, I see that this is explicitly listed as a difference from
the FHS.
https://www.debian.org/doc/debian-policy/ch-opersys.html
I'm told that some MIPS systems are putting libraries in subdirs for
the same reason as RISC-V, to handle the proliferation of supported
ABIs.
https://sourceware.org/pipermail/libc-alpha/2020-April/112503.html
It is easier to support a large number of ABIs if you group related
ones together in a directory tree instead of a flat file system.
Maciej's post mentioned above also points out that the standard
provides rationale for some decisions, but doesn't give a rationale
for the /lib<qual> limitation. Are there tools that require libraries
to be in a flat file system? I haven't seen any in the RISC-V
ecosystem yet, but maybe some distro vendors have tools that make this
assumption.
Also, as Maciej points out, this decision for the library layout was
likely made long ago when systems supported at most 3 ABIs. But now
that we have systems that support more ABIs, maybe it would make sense
to revisit this decision and allow libraries in subdirs?
Jim
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