On Wednesday 13 May 2009 18:03:57 Ian Lance Taylor wrote:
> Vladimir Kuznetsov <ks.vladimir@xxxxxxxxx> writes:
> > On Wednesday 13 May 2009 04:58:25 Ian Lance Taylor wrote:
> >> Vladimir Kuznetsov <ks.vladimir@xxxxxxxxx> writes:
> >> > I have a very small embedded kernel that uses a slightly modified
> >> > calling conventions than normal ones on x86-64: it uses r10 instead or
> >> > rcx to pass 4th argument and "syscall" instruction instead of normal
> >> > "call". I am using a thin wrapper like this:
> >> >
> >> > error_t __do_syscall(SyscallParams params, ...)
> >> > __asm__("__do_syscall"); __asm__(
> >> > "__do_syscall:\n"
> >> > " movq %rcx, %r10\n"
> >> > " syscall\n"
> >> > " ret\n"
> >> > );
> >> >
> >> > but it requires an additional function call (and so uses an additional
> >> > cache line and, possibly, a TLB entry). Are there any way to do it
> >> > inline ?
> >>
> >> You always want to use "syscall" instead of "call"?
> >
> > No, "syscall" is used only for system calls. I still have a normal
> > functions that are called using standard calling convention.
>
> If you only need it for system calls then I recommend writing an inline
> asm statement for each system call, and wrap that inline asm up in an
> inline function in a header file somewhere. If you mark the function
> with the always_inline attribute then you should get the results you
> want.
Yes, I will probably stick with this solution for now. Thanks for your
attention !
--
Best Regards,
Vladimir
