On Mon, Feb 11, 2013 at 11:30:50AM +0100, Jonas Bonn wrote: > >> Is this really true? Don't setcontext and friends require that _all_ > >> the registers be part of sigcontext? > > > > But for an ABI - callee saved regs will anyhow be saved/restored even in > > setcontext case ! So collecting it for that purpose seems useless, or am I missing > > something here. > > Yes, I agree with you on the ABI bit... but set/get/swapcontext are > special in that they use rt_sigreturn to "trick" the kernel into > swapping out _all_ registers; it's a light-weight (userspace) context > switch. > > (I really don't know this area very well, though, so I'm hoping > somebody more knowledgable jumps in here... Al?) I'd suggest asking itanic folks; they do *not* put callee-saved stuff into sigcontext. AFAICS, they don't have setcontext() implemented as a syscall at all - it's done as sigprocmask() + doing to callee-saved registers what longjmp() does. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
