code review 6209048: runtime: fix syscalls for netbsd

runtime: fix syscalls for netbsd

Use correct syscall numbers and arguments for NetBSD.
Provide a trampoline for signal returns (using signal API 3).

[jsing, 2012-05-10 15:01:01]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[rsc, 2012-05-10 15:30:11]

Exiting silently is a bad way to react to an unexpected failure.
Better to do what the other syscalls do:
 MOVL    $0xf1, 0xf1  // crash
The PC of the crash will tell us where the problem is.

Russ

[jsing, 2012-05-10 16:54:56]

On 2012/05/10 15:30:11, rsc wrote:
> Exiting silently is a bad way to react to an unexpected failure.
> Better to do what the other syscalls do:
>  MOVL    $0xf1, 0xf1  // crash
> The PC of the crash will tell us where the problem is.

Normally I would agree, however in this case we are still running in signal
context and will most likely have signals blocked (the setcontext syscall should
return us to process context). Triggering a SIGSEGV in this case does not make
for fun debugging... exiting with a 255 status code at least makes it a little
easier to know what failed.

[rsc, 2012-05-10 17:12:07]

LGTM

[jsing, 2012-05-10 17:48:52]

*** Submitted as http://code.google.com/p/go/source/detail?r=f359827334f4 ***

runtime: fix syscalls for netbsd

Use correct syscall numbers and arguments for NetBSD.
Provide a trampoline for signal returns (using signal API 3).

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/6209048