cmd/dist, pkg/runtime: Plan 9, 64-bit: Get PID from TLS; remove use of `_tos'.

cmd/dist, pkg/runtime: Plan 9, 64-bit: Get PID from TLS; remove use of `_tos'.

Using offsets from Tos is cumbersome and we've had problems
in the past. Since it's only being used to grab the PID, we'll just
get that from the default TLS instead.

[akumar, 2012-09-21 13:57:41]

Hello rsc@golang.org, rminnich@gmail.com, npe@plan9.bell-labs.com (cc:
golang-dev@googlegroups.com),

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

[rsc, 2012-09-21 14:32:51]

This only matters for pids above 2147483647, right? Did you actually
run into this? I'd rather make getpid return a uint64 and define pid
as uint64 than need to introduce casts in every comparison. That is,
the cast is a symptom that something else wasn't declared correctly.

Russ

[akumar, 2012-09-22 22:04:40]

PTAL.

On 2012/09/21 14:32:51, rsc wrote:
> This only matters for pids above 2147483647, right? Did you actually
> run into this? I'd rather make getpid return a uint64 and define pid
> as uint64 than need to introduce casts in every comparison. That is,
> the cast is a symptom that something else wasn't declared correctly.
> 
> Russ

We ran into this because of a difference of opinion about the
size of `long' between UNIX and Plan 9, while cross-compiling.
I apologize for the dirty hack. I've updated this to a more
appropriate solution.

I agree about getpid; I'll update it in another CL.


Thanks,
Akshat

[rminnich, 2012-09-23 00:03:25]

I like this one much better.

LGTM.

ron

[rsc, 2012-09-23 00:27:30]

http://codereview.appspot.com/6543049/diff/4002/src/pkg/runtime/sys_plan9_amd...
File src/pkg/runtime/sys_plan9_amd64.s (right):

http://codereview.appspot.com/6543049/diff/4002/src/pkg/runtime/sys_plan9_amd...
src/pkg/runtime/sys_plan9_amd64.s:109: MOVQ	procid(AX), AX
Does procid need to be defined? I can't seem to find it.

[akumar, 2012-09-23 00:42:35]

http://codereview.appspot.com/6543049/diff/4002/src/pkg/runtime/sys_plan9_amd...
File src/pkg/runtime/sys_plan9_amd64.s (right):

http://codereview.appspot.com/6543049/diff/4002/src/pkg/runtime/sys_plan9_amd...
src/pkg/runtime/sys_plan9_amd64.s:109: MOVQ	procid(AX), AX
On 2012/09/23 00:27:30, rsc wrote:
> Does procid need to be defined? I can't seem to find it.

From the change to cmd/dist/buildruntime.c:152 we have:
"#define        procid(r) 16(GS)\n"

It will placed in the generated file, zasm_plan9_amd64.h

[rsc, 2012-09-24 16:24:30]

LGTM

[rsc, 2012-09-24 16:24:49]

*** Submitted as http://code.google.com/p/go/source/detail?r=dd2b297d258d ***

cmd/dist, pkg/runtime: Plan 9, 64-bit: Get PID from TLS; remove use of `_tos'.

Using offsets from Tos is cumbersome and we've had problems
in the past. Since it's only being used to grab the PID, we'll just
get that from the default TLS instead.

R=rsc, rminnich, npe
CC=golang-dev
http://codereview.appspot.com/6543049

Committer: Russ Cox <rsc@golang.org>