I looked at the diff of the set of syscalls you provide and the ones
we've been using.
Specific questions:
- How do you propose representing the architecture-specific syscalls?
We have three "very special" syscalls that are negative numbers, which I
won't worry about, since they'll be out of the normal numbering
sequence. But we also have a few others (cmpxchg_baddr, raise_fpe,
flush_cache) that we'll need a numbering location for. I see that you
already have an empty block from 244 (today) to 1023; perhaps
architectures should just use 1023 on down? I'll do this for now.
- You renamed __NR__llseek to __NR_llseek, which of course seems pretty
reasonable, but libc expects to see the former (both glibc and uclibc).
Is it worth requiring non-standard libc code? I may just add
__NR__llseek as an alias in my unistd.h for now.
- Are you planning to keep all the ifdef'ed syscalls going forward?
Because honestly, I'd rather just enable __ARCH_WANT_SYSCALL_NO_AT,
etc., and use the kernel implementations, since otherwise I'll have to
go into both uclibc and glibc and add a bunch of extra Tilera-specific
code and then try to push that up to their community, when really I just
want to have the Tilera architecture userspace support be as generic as
possible.
The result seems positive overall; I'm certainly happy to dump, e.g.,
"nice" and "stime", since they have obvious userspace wrappers (and in
fact libc is already geared up to use them if available). And a few
other syscalls in the Tile list aren't even implemented but were just
brought over from x86 "in case", like afs_syscall, putpmsg, and getpmsg,
so I'm happy to abandon them as well. And "sysfs" is commented out of
uclibc, and not present in glibc, so no big loss there. Other than that
I think the set of supported syscalls will only change by a couple --
and more importantly, from my point of view, Tilera gets to stay
automatically synced to any new syscalls added to Linux going forward.
So this is good.
I assume that folks are committing to not changing any of the existing
numbers, ifdefs, etc. in asm-generic/unistd.h; if we're the only
architecture using it, no one might notice until we did. :-)
--
Chris Metcalf, Tilera Corp.
http://www.tilera.com
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