Bug 809938

Summary:	www-client/firefox: please consider to split up --with-fpu=neon and --with-thumb=yes
Product:	Gentoo Linux	Reporter:	tt_1 <herrtimson>
Component:	Current packages	Assignee:	Mozilla Gentoo Team <mozilla>
Status:	RESOLVED CANTFIX
Severity:	normal	CC:	sam
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---
Attachments:	suggested patch allow armv7a profiles to unforce thumb2

Description tt_1 2021-08-24 09:51:00 UTC

In src_configure the firefox config script does ask for special secondary rust target called 'thumbv7neon-unknown-linux-gnueabihf' if USE="+cpu_flags_arm_neon" is enabled. It is needed on top of armv7-unknown-linux-gnueabihf, since upstream only intends to provide it as a std lib archive. 

Right now, there is no way to enable the bootstrap of this special rust-std target 'thumbv7neon-unknown-linux-gnueabihf' in the dev-lang/rust ebuild, let alone the dev-lang/rust-bin ebuild. 

So we are trapped and forced to disable all neon support via USE="-cpu_flags_arm_neon", however --with-fpu=neon alone does work with standalone armv7-unknown-linux-gnueabihf rustc ; --with-thumb=yes alone demands the special rust-std 'thumbv7neon-unknown-linux-gnueabihf' to be present. 

A workaround would be to disable cpu_flags_arm_neon and inject --with-fpu=neon via env file, but thats rather odd. 

I will attach a split patch against firefox-91.0.1 ebuild later the evening.

Comment 1 tt_1 2021-08-25 10:31:40 UTC

Created attachment 735937 [details, diff]
suggested patch

Comment 2 tt_1 2021-08-25 10:32:47 UTC

there is still some work to be done for profiles, as CPU_FLAGS_ARM="thumb2" is forced on armv7a profiles, and also on aarch64

Comment 3 tt_1 2021-08-25 10:36:56 UTC

Created attachment 735939 [details, diff]
allow armv7a profiles to unforce thumb2

mask needs to be expanded to spidermonkey, thunderbird obviously

Comment 4 Joonas Niilola gentoo-dev

2023-07-05 07:50:11 UTC

Sorry this is a bit outdated now. We could use a fresh bug with _all_ steps included to get arm support in firefox, as we don't officially support arm currently.