Date: Mon, 3 Feb 2020 08:32:25 -0500 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Cc: Mark Corbin <mark@...sco.co.uk> Subject: Re: REG_SP Definition for RISC-V On Mon, Feb 03, 2020 at 11:42:30AM +0000, Mark Corbin wrote: > Hello > > I'm trying to fix a build issue with libsigsegv  for RISC-V when compiling > against musl 1.1.24 (under Buildroot). > > The build fails because the array index 'REG_SP' (for indexing into > uc_mcontext.__gregs) is not defined in arch/riscv64/bits/signal.h. This > constant is defined by glibc in sysdeps/unix/sysv/linux/riscv/sys/ucontext.h > > I was wondering whether the appropriate fix is just to add '#define REG_SP 2' to > the top of arch/riscv64/bits/signal.h ? (Note that there is a REG_SP definition > in arch/riscv64/bits/reg.h which isn't being included). > > Alternatively I could submit a patch to libsigsegv to modify the index into > the '__gregs' array to be '2' rather than 'REG_SP', however there could be > other glibc compatible RISC-V packages that make use of the 'REG_SP' > definition. > > I'm happy to generate and submit any patches as appropriate. Generally, we like to avoid this kind of REG_* (or even bare names) register macro in signal.h since it's highly namespace-polluting (can break software using them for its own purposes that has no knowledge that some arch has a reg by that name in its signal.h bits) and only expose them under _GNU_SOURCE when we do. Right now musl has them exposed via <sys/reg.h>. I'm not sure if there's any precedent for that or if glibc only has them in <signal.h> So my leaning would be to leave it as it is and ask applications to include <sys/reg.h> if they want these macros. But if it looks like this is contrary to what maintainers of other software want to do, we could consider putting them under _GNU_SOURCE with <signal.h> like many other archs do. Rich
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