Subject: Syscall conventions
To: None <>
From: Ben Harris <>
List: tech-kern
Date: 03/09/2000 14:43:46
While people are discussing syscalls, I have a question about them.

Looking at the various SYS.hs around in lib/libc/arch, it seems that a lot
of architectures do something like (this from arm32):

#define SYSTRAP(x)      swi SYS_ ## x
#define _SYSCALL_NOERROR(x,y)                                           \
        ENTRY(x);                                                       \
#define SYSCALL_NOERROR(x)                                              \

So the system call function doesn't have a return instruction.  Does this
mean that the kernel munges the registers on return from the system call
to return from the function as well?  Please tell me it doesn't!

Ben Harris
Unix Support, University of Cambridge Computing Service.