Messages in this thread | | | Subject | Re: PROBLEM: using _syscall4 to call sys_futex with -fPIC won't compile | From | Andreas Schwab <> | Date | Mon, 05 Jul 2004 19:57:03 +0200 |
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Chris Friesen <cfriesen@nortelnetworks.com> writes:
> The "_syscallx" macros are in the userspace versions of the kernel > headers, and as such should be fair game.
They are known not to work with -fpic (on x86 anyway, other architectures are less broken). Anyway, just because there is no #ifdef __KERNEL__ doesn't mean a kernel header is meant for user space use.
> Also, you need to get a list of syscall numbers somehow, and those > numbers are generally defined in the same file that contains the > "_syscallx" macros.
They are duplicated in <sys/syscall.h> (which is auto-generated from the list in <asm/unistd.h>).
> syscall() doesn't work for all system calls. The man page explicitly > warns that it doesn't work for pipe(2).
Only if pipe(2) uses the "two retvals" calling convention (Alpha and ia64, but not x86 or m68k). But then, pipe is already available without syscall(), and new syscalls normally use simple enough calling conventions that are suitable for syscall().
Andreas.
-- Andreas Schwab, SuSE Labs, schwab@suse.de SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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