12.13.0 build from scratch fails on RPi3 Raspian

[btsimonh]

• Version: 12.13.0
• Platform: Raspberry Pi 3, Raspbian -
  pi@raspberrypi:~ $ uname -a
  Linux raspberrypi 4.19.75-v7+ Unable to decrypt aes-256-cbc created by PHP  #1270 SMP Tue Sep 24 18:45:11 BST 2019 armv7l GNU/Linux
• Subsystem: V8 linking, (Node linking?)

In order to build NodeJS from scratch on raspbian, libatomic is needed in v8.gyp so that makesnapshot links.

I believe Raspian has an arm6l kernel, even thought the CPU reports as arm7l.

I also understand that arm6l is no longer built as an official binary, and that I should not expect to build without some pain :).

I am testing a change in v8.gyp:
line 796:

        # Platforms that don't have Compare-And-Swap (CAS) support need to link atomic library
        # to implement atomic memory access
        ['v8_current_cpu in ["mips", "mipsel", "mips64", "mips64el", "ppc"]', {
          'link_settings': {
            'libraries': ['-latomic', ],
          },
        }],

to

        # Platforms that don't have Compare-And-Swap (CAS) support need to link atomic library
        # to implement atomic memory access
        ['v8_current_cpu in ["mips", "mipsel", "mips64", "mips64el", "ppc", "arm"]', {
          'link_settings': {
            'libraries': ['-latomic', ],
          },
        }],

I am no expert on this, so I'm not sure that including "arm" covers too many platforms....

Compilation now continues - I will report final results in some hours (build is slow on RPi...).

Failure was when linking v8's mksnapshot.

I also note that the NodeJS makefiles also lack -latomic, and so have temporarily modified node.gyp to enable it:
line 295:

      ['(OS=="linux" or OS=="mac")', {
        'libraries': ['-latomic'],
      }],

to

      ['(OS=="linux" or OS=="mac") and llvm_version!=0', {
        'libraries': ['-latomic'],
      }],

I know this is an unsuitable mod - Advice on a better cross platform mod appreciated.

p.s. the armv7 binary runs happily on Raspbian on RPi3 - but is unlikely to work on RPiZero or Rpi1 (please correct me if I am wrong...)? There are millions of these devices out in the wild, and continued NodeJS support for them would be nice - e.g. for Node-Red use.

[af4ex]

I too was getting 'atomic' errors in building 12.13.0 on my new RPi4. I can see the libatomic runtime is installed on the system (buster), so apparently RASPIAN does use it.

But I had to do a "sudo apt install libatomic-ops-dev" to get it to link, after adding -latomic to the link settings in v8.gyp

[btsimonh]

just a note:
The resulting executable built on Raspbian Buster on RPi3 is armv6 compatible - i'm no expert, but the readelf hints at this, and it does run on RPiZero. I don't think I specifically installed libatomic dev libraries, but was building via nexe.

[gireeshpunathil]

@btsimonh -does #30099 fix this issue? or only part of it?

[btsimonh]

i got a shiny rpi4 for xmas which is still in the box; will see if I can get time this week to put a fresh OS on it and try a build. At least the build time should be about a 1/4 of the time compared to my RPi3...
@af4ex - are you in a position to test a build including this commit?

[btsimonh]

Seems like a silly observation;
Would statically linking libatomic be a bad thing to avoid all the to-ing and fro-ing about it?

I have a hacked version of node.gyp which caused libatomic to be needed for amazon linux 2 (I copied my rpi config) - I corrected this and got a viable executable (I did not notice at first, because the build process itself installs libatomic, so testing on the platform you build on is invalid). (12.13.0)

I just tested changing
'libraries': ['-latomic'],
to
'libraries': ['-l:libatomic.a'],

and the exe no longer needs libatomic according to ldd

Am I barking up the wrong tree? Does libatomic, when compiled on a system which has the required features, just become an empty library?

[bnoordhuis]

With v12.x out of support and this issue not having seen activity in 2.5 years, I'll go ahead and close it out.