Crashpad for a Linux/ARM32 platform?

[Gerrit Telkamp]

Hi,

I assume that Crashpad can be built for a Linux/arm32 platform, because Chromium does. We use a NXP i.MX6 UltraLite (ARM Cortex-A7), running Yocto Linux.

But the library minidump/chromium supports arm64 CPUs only (besides x86 and x64, see build/config/BUILD.gn). Is there someone who has managed to build minidump for arm32 platforms? Or is there a simple readme how to twist the Build.gn to build it for a Linux/arm32 platform?

Thanks, Gerrit

[Joshua Peraza]

Yes, Crashpad-linux should generally work for ARM32. I think it's just third_party/mini_chromium hasn't been setup for that cross-build because we normally do build in chromium when targeting ARM.

I think it shouldn't be too much work to get the ARM build working in mini_chromium. You can add compiler switches for your target arch by extending the if/elses around here: https://chromium-review.googlesource.com/c/chromium/mini_chromium/+/2559153

I think pairing that with Crashpad's target_sysroot gn arg should get you close. 

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[丁毅]

I tried to modify the BUILD.gn file and set target_sysroot to an arm64 sysroot, but many build/link error occurs, such as:

/usr/bin/ld: cannot find crti.o: No such file or directory

/usr/bin/ld: cann't find -ldl

...

[Joshua Peraza]

It sounds like you might be missing some important dev packages in your sysroot, in this case a dev libc package.

[丁毅]

Thanks, it works for ARM64(arm32 is similar, I thought) now! The steps are:

1. Download sysroot for ARM64 from: https://commondatastorage.googleapis.com/chrome-linux-sysroot/toolchain/5d3cca0a256424f2d0a2ecdfe95203d555b5e135/debian_sid_arm64_sysroot.tar.xz

2. modify the code in third_party/mini_chromimu/mini_chromimu/build/config/BUILD.gn:

  if (mini_chromium_is_linux) {

  defines = [ "_FILE_OFFSET_BITS=64" ]
  common_flags += [ "-pthread" ]
  if (current_cpu == "x86") {
    common_flags += [
          "-m32",
    ]
  } else if (current_cpu == "x64") {
    common_flags += [
          "-m64",
    ]
  } else {
    assert(false, "Unsupported architecture")
  }
  ...

TO:

 if (mini_chromium_is_linux) {

  defines = [ "_FILE_OFFSET_BITS=64" ]
  common_flags += [ "-pthread" ]
  if (current_cpu == "x86") {
    common_flags += [
          "-m32",
    ]
  } else if (current_cpu == "x64") {
    common_flags += [
          "-m64",
    ]
  } else if (current_cpu == "arm64") {
    common_flags += [
          "--target=aarch64-linux-gnu",
    ]
  } else {
    assert(false, "Unsupported architecture")
  }
  ...

3. The gn command:

gn gen out/linux/arm64/Release --args='

target_sysroot="/home/dingyi/Downloads/debian_sid_arm64_sysroot"

target_cpu="arm64"

target_os="linux"

is_debug=false

'

4. ninja -C out/linux/arm64/Release

[丁毅]

Update! It works for arm64, armhf and armel, take arm64 as example, the steps are:

  }  else if (current_cpu == "arm") {

    common_flags += [

      "--target=arm-linux-gnueabihf",

      "-mfloat-abi=hard",

    ]

  } else if (current_cpu == "armel") {

    common_flags += [

      "--target=arm-linux-gnueabi",

      "-mfloat-abi=softfp",

    ]

    ldflags += [

      "-latomic",

    ]

  } else {

    assert(false, "Unsupported architecture")
  }
  ...

3. The gn command:

gn gen out/linux/arm64/Release --args='

target_sysroot="/home/dingyi/Downloads/debian_sid_arm64_sysroot"

target_cpu="arm64"

target_os="linux"

is_debug=false

'

4. ninja -C out/linux/arm64/Release