Re: Problem with syscall_disestablish() - PR kern/50430

[Eric Haszlakiewicz <erh%nimenees.com@localhost>]

On November 19, 2015 4:28:46 AM EST, Paul Goyette <paul%vps1.whooppee.com@localhost> wrote:
>And if there's anyone who really understands HOW the initial syscall
>gets interrupted when the signal is being delivered (and HOW it gets
>restarted when the handler returns) I would love an explanation!
>

Regarding restart, I don't think it needs to be explicitly saved anywhere, because the original call in the userland program has the necessary information.

E.g. if you look at the restart path for alpha (just because that's the first search result I found) you see that it simply moves the userland process' program counter back a bit, and let's the process trigger the syscall again:
http://nxr.netbsd.org/xref/src/sys/arch/alpha/alpha/syscall.c#203

Dunno about how it's actually interrupted though.

Eric