Building formulae from source on aarch64 keeps automatically symlinking to /lib64/ld-linux-x86-64.so.2

[heaths]

Additional Info

• I am using Windows Subsystem for Linux

Output of brew config

HOMEBREW_VERSION: 4.5.2
ORIGIN: https://github.com/Homebrew/brew
HEAD: 6f39076b3c2251994419215279d0525ef667fc31
Last commit: 12 days ago
Branch: stable
Core tap JSON: 21 May 23:34 UTC
HOMEBREW_PREFIX: /home/linuxbrew/.linuxbrew
HOMEBREW_BROWSER: wslview
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: :0
HOMEBREW_EDITOR: hx
HOMEBREW_MAKE_JOBS: 12
Homebrew Ruby: 3.4.3 => /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/vendor/portable-ruby/3.4.3/bin/ruby
CPU: dodeca-core 64-bit arm
Clang: 20.1.5
Git: 2.43.0 => /bin/git
Curl: 8.5.0 => /bin/curl
Kernel: Linux 5.15.167.4-microsoft-standard-WSL2 aarch64 GNU/Linux
OS: Ubuntu 24.04.2 LTS (noble)
WSL: 2 (Microsoft Store)
Host glibc: 2.39
/usr/bin/gcc: 13.3.0
/usr/bin/ruby: N/A
glibc: N/A
gcc@11: N/A
gcc: 14.2.0_1
xorg: N/A

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: The following formulae have the same name as core formulae:
  jandedobbeleer/oh-my-posh/oh-my-posh
Some of these can be resolved with:
  brew untap jandedobbeleer/oh-my-posh

Warning: Your CPU architecture (arm64) is not supported. We only support
x86_64 CPU architectures. You will be unable to use binary packages (bottles).

This is a Tier 2 configuration:
  https://docs.brew.sh/Support-Tiers#tier-2
Do not report any issues to Homebrew/* repositories!
Read the above document instead before opening any issues or PRs.

Description of issue

I'm trying to run brew install --build-from-source gh, for example, but every time on a do on an aarch64 machine set up to cross-build for amd64, /home/linuxbrew/.linuxbrew/lib/ld.so gets symlinked to /lib64/ld-linux-x86-64.so.2 and I can't figure out why. I've deleted /home/linuxbrew/.linuxbrew/lib/ld.so and symlinked to /lib/ld-linux-aarch64.so.1 numerous times. Any installed formulae and even brew doctor and brew config work until I re-run a command like brew install --build-from-source {formulae}.

To repro on my system:

$ ls -l /home/linuxbrew/.linuxbrew/lib/ld.so
lrwxrwxrwx 1 root root 26 May 21 16:40 /home/linuxbrew/.linuxbrew/lib/ld.so -> /lib/ld-linux-aarch64.so.1

$ brew install --build-from-source gh
gh 2.72.0 is already installed but outdated (so it will be upgraded).
Warning: Your CPU architecture (arm64) is not supported. We only support
x86_64 CPU architectures. You will be unable to use binary packages (bottles).

This is a Tier 2 configuration:
  https://docs.brew.sh/Support-Tiers#tier-2
Do not report any issues to Homebrew/* repositories!
Read the above document instead before opening any issues or PRs.

==> Fetching gh
==> Downloading https://raw.githubusercontent.com/Homebrew/homebrew-core/6e524fb47e61d295a2c73a125e472a690f556b54/Formula/g/gh.rb
Already downloaded: /home/heaths/.cache/Homebrew/downloads/deae80d3dd1d05351e22804638b21506610a47bf534e5dd0359cee2b6f07f2ed--gh.rb
==> Downloading https://github.com/cli/cli/archive/refs/tags/v2.73.0.tar.gz
Already downloaded: /home/heaths/.cache/Homebrew/downloads/c9977ee941167417ad194687ad0c2250afaef6d3e40300260112ff73fc674a15--cli-2.73.0.tar.gz
==> Upgrading gh
  2.72.0 -> 2.73.0
Error: An exception occurred within a child process:
  Errno::ELIBBAD: Accessing a corrupted shared library - /home/linuxbrew/.linuxbrew/bin/gcc-14

$ ls -l /home/linuxbrew/.linuxbrew/lib/ld.so
lrwxrwxrwx 1 heaths heaths 27 May 21 16:49 /home/linuxbrew/.linuxbrew/lib/ld.so -> /lib64/ld-linux-x86-64.so.2

Notice how it points back to /lib64/ld-linux-x86-64.so.2. I'm not sure how or why this happens.

I'm using ubuntu-24.04 and added am64 arch support. A few packages are installed e.g.,

$ apt list --installed | grep amd64

gcc-14-base/noble-updates,noble-security,now 14.2.0-4ubuntu2~24.04 amd64 [installed,automatic]
libasan8-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libatomic1-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libc6-amd64-cross/noble,noble,now 2.39-0ubuntu8cross1 all [installed]
libc6-dev-amd64-cross/noble,noble,now 2.39-0ubuntu8cross1 all [installed,automatic]
libc6/noble-updates,noble-security,now 2.39-0ubuntu8.4 amd64 [installed]
libgcc-13-dev-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 13.3.0-6ubuntu2~24.04cross1 all [installed,automatic]
libgcc-s1-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libgcc-s1/noble-updates,noble-security,now 14.2.0-4ubuntu2~24.04 amd64 [installed,automatic]
libgomp1-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libhwasan0-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libidn2-0/noble-updates,now 2.3.7-2build1.1 amd64 [installed,automatic]
libitm1-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
liblsan0-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libquadmath0-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libstdc++6-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libtsan2-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libubsan1-amd64-cross/noble-updates,noble-updates,noble-security,noble-security,now 14.2.0-4ubuntu2~24.04cross1 all [installed,automatic]
libunistring5/noble-updates,now 1.1-2build1.1 amd64 [installed,automatic]
linux-libc-dev-amd64-cross/noble,noble,now 6.8.0-25.25cross1 all [installed,automatic]
pkg-config/noble,now 1.8.1-2build1 amd64 [installed]
pkgconf/noble,now 1.8.1-2build1 amd64 [installed,automatic]

[heaths]

Tracing even a dry-run, I see brew is updating ld.so:

$ strace brew install --build-from-source -n gh

...
newfstatat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/opt/glibc/bin/ld.so", 0xfffff9e891f8, 0) = -1 ENOENT (No such file or directory)
newfstatat(AT_FDCWD, "/lib64/ld-linux-x86-64.so.2", {st_mode=S_IFREG|0755, st_size=236616, ...}, 0) = 0
geteuid()                               = 1000
getegid()                               = 1000
getuid()                                = 1000
getgid()                                = 1000
faccessat(AT_FDCWD, "/lib64/ld-linux-x86-64.so.2", X_OK) = 0
newfstatat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib/ld.so", {st_mode=S_IFREG|0755, st_size=203968, ...}, 0) = 0
geteuid()                               = 1000
getegid()                               = 1000
getuid()                                = 1000
getgid()                                = 1000
faccessat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib/ld.so", R_OK) = 0
readlinkat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib/ld.so", "/lib/ld-linux-aarch64.so.1", 100) = 26
newfstatat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib", {st_mode=S_IFDIR|0775, st_size=40960, ...}, 0) = 0
newfstatat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib/ld.so", {st_mode=S_IFREG|0755, st_size=203968, ...}, 0) = 0
unlinkat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib/ld.so", 0) = 0
symlinkat("/lib64/ld-linux-x86-64.so.2", AT_FDCWD, "/home/linuxbrew/.linuxbrew/lib/ld.so") = 0
mmap(NULL, 131072, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xff13cc720000
munmap(0xff13cc720000, 65536)           = 0
newfstatat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/opt/glibc/bin/ld.so", 0xfffff9e891f8, 0) = -1 ENOENT (No such file or directory)
newfstatat(AT_FDCWD, "/home/linuxbrew/.linuxbrew/opt/gcc", {st_mode=S_IFDIR|0755, st_size=4096, ...}, 0) = 0
...

According to brew info glibc, it's not installed.

I removed /etc/ld.so.cache and rebuilt it. ldconfig -p shows only aarch64 libraries but even after all that, the above steps - re-symlinking ld.so and doing a dry-run install - still overwrites the symlink to point to /lib64/ld-linux-x86-64.so.2.

[heaths]

This appears to be because of Homebrew/Library/Homebrew/extend/os/linux/install.rb. Since I don't have glibc installed via brew, seems it's falling back to a fixed list that checks for /lib64/ld-linux-x86-x64.so.2 first. So maybe I just need to brew install glibc?

[heaths]

The glibc formulae is older than my system, so how do I prevent brew from choosing the wrong path? I have no HOMEBREW_PREFIX/"etc/ld.so.conf" or anything like that, but can find no documentation that would work or is supported. Is there some other way?

For now, I've just removed the /lib64 symlink. I've been unable to remove multiarch support (some packages are hard dependencies I can't seem to forcibly remove now), so I might just have to blow away this WSL distro and start over. Keep xplat development in a container next time.

[Bo98]

The Homebrew glibc is pretty much only used for those on older glibc rather than your case. This is intentional as the system one is better if new enough.

aarch64 is still WIP - I'll look into multiarch support. I don't know any workarounds so all I can say is that multiarch isn't supported yet.

[heaths]

Understood. That's why I posted here as well, having noticed your issue template (or wherever I saw it). 😉 I appreciate it's a work in progress. Maybe a simple solution is to change that fallback list based on the current host architecture at the very list. It's simple to the point of being naive, but seems in line with what's there now which seems to be targeting amd64 machines set up to xplat with aarch64. Basically just need the reverse.

[heaths]

What's odd is that it had been working. Could this be because I was working on a formulae to eventually build a bottle, but ended up pulling in gcc and that started this chain? My system had been configured for xplat for a while before that with no problems. It's not clear what might've triggered this.