892355 - Elfhack is disabled in Fennec since version 20

Status: RESOLVED FIXED

(Firefox Build System :: General, defect)

Description

[Mike Hommey [:glandium]]

I guess this happened when switching to a new NDK, where the default for PT_GNU_RELRO segments changed, and that disabled elfhack. This mad memory footprint 2.5MB larger than with elfhack, and the apk around 350KB larger.

(Note that for aurora and m-c, elfhack is disabled for another reason: the profiler, but that's for a separate bug)

Comment 1

[Mike Hommey [:glandium]]

Attachment: Force enable elfhack with --enable-elf-hack

This makes --enable-elf-hack error out if elfhack can't be enabled, or have configure do what it can to keep it enabled (by disabling unsupported linker features)

Comment 2

[Mike Hommey [:glandium]]

Attachment: Force enable elfhack with --enable-elf-hack

With missing --disable-elf-hack in mozconfigs that --enable-profiling

Comment 3

[Mike Hommey [:glandium]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/f138a2a6c329

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/f138a2a6c329

Comment 5

[Alex Keybl [:akeybl]]

Let's take this in FF24 so that it gets a full beta cycle to iron out any issues.

Comment 6

[Mark Banner (:standard8)]

Comment on attachment 773807 [details] [diff] [review]
Force enable elfhack with --enable-elf-hack

Review of attachment 773807 [details] [diff] [review]:
-----------------------------------------------------------------

::: build/unix/mozconfig.linux
@@ +2,5 @@
>  
>  CC="/tools/gcc-4.7.2-0moz1/bin/gcc"
>  CXX="/tools/gcc-4.7.2-0moz1/bin/g++"
> +
> +ac_add_options --enable-elf-hack

Did you mean to --enable-elf-hack for linux 32 as well? If so, then I think you want to update mozconfig.linux32 as well.

Comment 7

[Mike Hommey [:glandium]]

(In reply to Mark Banner (:standard8) from comment #6)
> >  CC="/tools/gcc-4.7.2-0moz1/bin/gcc"
> >  CXX="/tools/gcc-4.7.2-0moz1/bin/g++"
> > +
> > +ac_add_options --enable-elf-hack
> 
> Did you mean to --enable-elf-hack for linux 32 as well? If so, then I think
> you want to update mozconfig.linux32 as well.

mozconfig.linux32 includes mozconfig.linux.

Comment 8

[(no longer active)]

This obviously broke the profiling branch's cron job which merges automatically from m-c and removes --enable-profiling.  To fix that, I removed both --enable-profiling and --disable-elf-hack from linux32/64 mozconfigs.

glandium, is that the right thing to do?

Comment 9

[Mike Hommey [:glandium]]

(In reply to :Ehsan Akhgari (needinfo? me!) from comment #8)
> This obviously broke the profiling branch's cron job which merges
> automatically from m-c and removes --enable-profiling.  To fix that, I
> removed both --enable-profiling and --disable-elf-hack from linux32/64
> mozconfigs.
> 
> glandium, is that the right thing to do?

That sounds good to me.

Comment 10

[Kartikaya Gupta (email:[e-mail])]

This broke my local build because I include mobile/android/config/mozconfigs/common in my mozconfig, and so --enable-elf-hack got included into my mozconfig when it wasn't previously. My build failed on OS X because the host compiler couldn't find elf.h (included from elfxx.h). I had to put --disable-elf-hack into my mozconfig to get past this error.

Comment 11

[(no longer active)]

(In reply to comment #10)
> This broke my local build because I include
> mobile/android/config/mozconfigs/common in my mozconfig

As far as I know, these mozconfigs are not supposed to be used by developers, unless they're expecting to keep up with stuff changing in them.  :/

Comment 12

[Kartikaya Gupta (email:[e-mail])]

That's not what I heard, but ok.

Comment 13

[Nick Alexander :nalexander [he/him] (PTO Feb 24-March 3)]

(In reply to :Ehsan Akhgari (needinfo? me!) from comment #11)
> (In reply to comment #10)
> > This broke my local build because I include
> > mobile/android/config/mozconfigs/common in my mozconfig
> 
> As far as I know, these mozconfigs are not supposed to be used by
> developers, unless they're expecting to keep up with stuff changing in them.
> :/

I had the same issue.  And we've been pointing new developers to the in-tree configs in #mobile for some time now.

Comment 14

[Mike Hommey [:glandium]]

Comment on attachment 773807 [details] [diff] [review]
Force enable elfhack with --enable-elf-hack

[Approval Request Comment]
Bug caused by a change in the used NDK 
User impact if declined: Memory footprint regression since FF20.
Testing completed (on m-c, etc.): Landed on m-c some time ago.
Risk to taking this patch (and alternatives if risky): Low. Build config only.
String or IDL/UUID changes made by this patch: None.

Comment 15

[bhavana bajaj [:bajaj]]

Comment on attachment 773807 [details] [diff] [review]
Force enable elfhack with --enable-elf-hack

Approving given this is low risk and comment# 5.

Comment 16

[Mike Hommey [:glandium]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/0d2724681600

Note the patches to browser/config/mozconfigs/linux*/nightly were left out on aurora because there is not --enable-profiling in those files on aurora. There is, however, one in mobile/android/config/mozconfigs/android/nightly, so that one is patched to disable elf hack as on m-c.