code review 94670047: cmd/ld: correctly compute note size on NetBSD.

cmd/ld: correctly compute note size on NetBSD.

Patch from http://gnats.NetBSD.org/48811.

[bsiegert, 2014-05-20 19:28:26]

Hello golang-codereviews@googlegroups.com (cc: tk@giga.or.at),

I'd like you to review this change to
https://code.google.com/p/go

[minux1, 2014-05-20 19:39:49]

see also https://codereview.appspot.com/98290043/

iant think that won't change anything.

[iant, 2014-05-20 20:45:07]

On Tue, May 20, 2014 at 12:39 PM, minux <minux.ma@gmail.com> wrote:
> see also https://codereview.appspot.com/98290043/
>
> iant think that won't change anything.

Yes, I may be missing something, but when I calculate the existing
value I come up with 7 + 4 + 1 == 12, and when I calculate the new
value i come up with rnd(7, 4) + rnd(4, 4) == 8 + 4 == 12.  So why
does this patch change anything?

Ian

[tk, 2014-05-21 11:10:26]

On Tue, May 20, 2014 at 01:45:06PM -0700, Ian Lance Taylor wrote:
> On Tue, May 20, 2014 at 12:39 PM, minux <minux.ma@gmail.com> wrote:
> > see also https://codereview.appspot.com/98290043/
> >
> > iant think that won't change anything.
> 
> Yes, I may be missing something, but when I calculate the existing
> value I come up with 7 + 4 + 1 == 12, and when I calculate the new
> value i come up with rnd(7, 4) + rnd(4, 4) == 8 + 4 == 12.  So why
> does this patch change anything?

I think the point is that the suggested calculation (using rnd) in the
patch is the correct one, while the current state (+1) is correct by
guessing or perhaps by reasoning. However, it only recently became
correct when this patch was applied:

-       sh->size = n;
+       sh->size = n - resoff % 4;

Before this change, the "+1" was just wrong, though ignored by older
NetBSD kernels. Newer NetBSD kernels are pickier.

1.2.1, which does not have the "-resoff%4" part, currently is wrong
for this reason. 1.2.1 needs the attached patch to work on NetBSD-current.
 Thomas

[iant, 2014-05-21 13:13:40]

LGTM

[iant, 2014-05-21 13:18:53]

*** Submitted as https://code.google.com/p/go/source/detail?r=59a0284a32de ***

cmd/ld: correctly compute note size on NetBSD.

Patch from http://gnats.NetBSD.org/48811.

LGTM=iant
R=golang-codereviews, minux.ma, iant
CC=golang-codereviews, tk
https://codereview.appspot.com/94670047

Committer: Ian Lance Taylor <iant@golang.org>