On Fri, Aug 19, 2022 at 2:14 AM Joerg Vehlow <lkml@jv-coder.de> wrote:

> Why is this even split up into two asm instructions?
> I guess there is nothing, that prevents the compiler from reordering the
> asm instructions, because it does not know, that they have side effects
> (they are not marked volatile).
>
> asm volatile ("syscall" : : "a"(__NR_tkill), "D"(pid), "S"(SIGHUP):
> "rax", "rcx", "r11");
>

I tried this and clang complains that the "Asm-specifier for input or
output variable conflicts with asm clobber list" for rax.  Should it be

  asm volatile ("syscall" : : "a"(__NR_tkill), "D"(pid), "S"(SIGHUP) :
"rcx", "r11");

instead?  Is it implicit that __NR_tkill is going into rax so it will be
clobbered?

Thanks,
Edward