[Bug 1711337] Re: Firefox crashes at start on armv7L after 55.0.1 update

[herrtimson]

I wrote an email to Chris Coulson, asking for some assistance with the
cflags. Hopefully he'll read it.

What you're saying about hardware requirements is not really true.
Firefox is pretty demanding in terms of memory, yes, but per job mostly.
On amd64 and if you build with gcc, it needs roughly 700 to 800 mb of
ram per thread, and roughly double as much if you pass debug cflags
along. Thats as bad as it gets, the demand in ram decreases a lot if you
take clang instead, which is also a little bit faster and the binary
seems to be a little bit faster as well (I'm actually writing this post
from a clang built firefox) However, situation on armhf is more tense,
because if you aim to compile nativly they are often limited by the
amount of ram per job. rpi2 has only ~900mb free available at boot time,
so we end up with just 200mb per core. This is not enough if you use gcc
for compilation, the device would swap a lot, whereas with with -j2 and
400mb per thread it only swaps during some hefty code sections around
the java script engine and close to the finish of the build, during
linking.

Swapping can be so slow, that it completly eats away the theoretical
speed gain by allowing more cores to be used with make via -jN

Also I would like to mention that we propably have to stick to gcc for
compilation, because you can use clang to compile firefox on amd64, but
not on armhf, due to a linking error. I think it is the same as in #72
of this bug report:

../../media/libstagefright/Unified_cpp_media_libstagefright1.o: In function `stagefright::SampleIterator::getChunkOffset(unsigned int, long long*)':
../../media/libstagefright/Unified_cpp_media_libstagefright1.cpp:(.text+0x554): undefined reference to `free'
../../media/libstagefright/Unified_cpp_media_libstagefright1.o: In function `stagefright::SampleIterator::getSampleSizeDirect(unsigned int, unsigned int*)'

At the moment trying to use gold linker instead of bfd, we'll see if
that makes a difference.

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Title:
  Firefox crashes at start on armv7L after 55.0.1 update

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