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Bug 707342 - www-client/firefox please re-add option to disable jit
Summary: www-client/firefox please re-add option to disable jit
Status: RESOLVED WONTFIX
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Mozilla Gentoo Team
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-01-30 01:51 UTC by Fedja Beader
Modified: 2020-02-05 22:23 UTC (History)
1 user (show)

See Also:
Package list:
Runtime testing required: ---

Attachments
Add USE=jit to www-client/firefox-68-4-2 (patch.patch,1010 bytes, patch)
2020-01-30 01:51 UTC, Fedja Beader 		Details | Diff
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Description Fedja Beader 2020-01-30 01:51:35 UTC 
Created attachment 608580 [details, diff]
Add USE=jit to www-client/firefox-68-4-2

Mozilla folks say that the --disable-ion options does it, and I can confirm that it indeed makes Firefox slow as all hell.

This should add another layer to CPU bug mitigation, by preventing bad js from being directly executed on CPU. But I have not done a detailed analysis of it.


Relevant preferences options, have not tested if they do what they say they do:

pref("javascript.options.baselinejit", false); // This should be enough
pref("javascript.options.ion", false);
pref("javascript.options.wasm_baselinejit", false);
pref("javascript.options.wasm_ionjit", false);
Comment 1 Jory A. Pratt gentoo-dev 2020-02-05 22:23:56 UTC 
You are welcome to use EXTRA_ECONF to disable jit yourself, I am not interested in supporting this configuration in Gentoo.