cheribuild.py hangs on Ubuntu 18.04 about cheribuild HOT 11 CLOSED

That means cat is blocked trying to do a fctl(F_SETLKW) on the METALOG in your rootfs directory. Is your data drive formatted/mounted in a way that would stop that working? Did you kill a previous run and possibly leave that file still locked?

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(specifically, /home/bharadwaj/datadrive/github/src/CHERI/output/rootfs-purecap128/METALOG in your case)

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Ah, you're building a sysroot, so a different output directory, but the METALOG /dev/null also shows it's trying to lock that. You should find that echo foo | cat -l >> /dev/null similarly hangs. Either your /dev/null is broken or something else hasn't released that lock. (Yes, the lock is unnecessary in this very specific case, but it's not worth optimising for that)

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I was wondering about the -l option of the cat command. It is not honored by the cat command on Linux.

$ echo foo | cat -l >> /dev/null
cat: invalid option -- 'l'
Try 'cat --help' for more information.
$ cat -l >> ~/foo
cat: invalid option -- 'l'
Try 'cat --help' for more information.

Do you think it would help if I remove the -l option from cat command? If so, can you point me to the source location?

Thanks!

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Correct, it's a BSDism. If you remove the -l, it will work for building a sysroot, but break horribly when trying to assemble a rootfs for a disk image. That is not the right answer. @arichardson is cat meant to be a bootstrap tool?

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@jrtc27 Yes, cat is bootstrapped from the CheriBSD tree. We could modify it to skip locking for /dev/null?

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We could, but that's an upstream FreeBSD issue, and is just unnecessary serialisation. There is a more fundamental bug going on here, given this is meant to work and we have many people successfully using Linux to build CheriBSD.

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FWIW, my cheribuild checkout contains

diff --git a/pycheribuild/projects/cross/cheribsd.py b/pycheribuild/projects/cross/cheribsd.py
index deaa811c..942d384b 100644
--- a/pycheribuild/projects/cross/cheribsd.py
+++ b/pycheribuild/projects/cross/cheribsd.py
@@ -805,7 +805,7 @@ class BuildFreeBSD(BuildFreeBSDBase):
             # By default also create a sysroot when installing world
             installsysroot_args = install_world_args.copy()
             # No need for the files in /usr/share and the METALOG file
-            installsysroot_args.set(NO_SHARE=True, METALOG="/dev/null")
+            installsysroot_args.set(NO_SHARE=True)
             installsysroot_args.set_env(DESTDIR=self.get_corresponding_sysroot())
             if sysroot_only:
                 if not self.has_installsysroot_target:

because I ran into something similar in the past. Apparently the docker daemon has been known to lock /dev/null (e.g., moby/moby#31182). Hilarious.

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@nwf could you commit this? I only added the /dev/null to avoid creating a METALOG file in the sysroot.

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FWIW, my cheribuild checkout contains

diff --git a/pycheribuild/projects/cross/cheribsd.py b/pycheribuild/projects/cross/cheribsd.py
index deaa811c..942d384b 100644
--- a/pycheribuild/projects/cross/cheribsd.py
+++ b/pycheribuild/projects/cross/cheribsd.py
@@ -805,7 +805,7 @@ class BuildFreeBSD(BuildFreeBSDBase):
             # By default also create a sysroot when installing world
             installsysroot_args = install_world_args.copy()
             # No need for the files in /usr/share and the METALOG file
-            installsysroot_args.set(NO_SHARE=True, METALOG="/dev/null")
+            installsysroot_args.set(NO_SHARE=True)
             installsysroot_args.set_env(DESTDIR=self.get_corresponding_sysroot())
             if sysroot_only:
                 if not self.has_installsysroot_target:

because I ran into something similar in the past. Apparently the docker daemon has been known to lock /dev/null (e.g., moby/moby#31182). Hilarious.

That change worked for me. Just providing feedback, in case you find it helpful.

Thanks to @jrtc27, @arichardson and @nwf for the quick responses. Really appreciate it.

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@arichardson: Done. Hopefully nobody noticed my tripping over the git UI again. (Sigh.)

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