Re: asm-generic/unistd.h and glibc use of NR_ipc

[Arnd Bergmann <arnd at arndb dot de>]

On Tuesday 28 September 2010, Linas Vepstas wrote:
> I'm trying to figure out the status of glibc w.r.t the latest linux
> unistd syscall interface, specifically, the status of the NR_ipc
> syscall.   Currently, I see the following:
> 
> -- Circa June 2009, Arnd Bergman introduced asm-generic/unistd.h
> (into the linux kernel) to provide a generic interface to system
> calls. It does *not* define NR_ipc, and instead provides
> NR_msgsnd, msgrcv, msgget, msgctl etc. syscalls.
> 
> -- Current glibc (2.12.1, as well as the current eglibc) does
> not appear to use these new calls anywhere. Instead, glibc
> has generic (non-arch-specific) implementations of msgsnd
> etc.  that use the old NR_ipc interface (see, e.g.
> sysdeps/unix/sysv/linux/msgsnd.c, semget.c, shmdt.c, msgrcv.c,
> shmget.c, etc.)
> 
> Is someone working on patches to get glibc to use the new
> syscall interfaces (for IPC)?  Am I missing something? Seems like
> any arch wishing to use asm-generic/unistd.h and get glibc working
> gets to break new ground, here ... right?

Chris Metcalf is using the generic unistd.h file on the tile architecture
and has a glibc port that should be easily portable to all future
architectures. There are a few of them getting ready to be merged
now (c6x, lm32, nios2, and some people have contacted me privately
for architectures I cannot name).

I expect that all of them will just use the same syscall ABI and glibc
port.

	Arnd