GNU bug report logs -
#42227
BPF in linux-libre
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Reported by: Mathieu Othacehe <othacehe <at> gnu.org>
Date: Mon, 6 Jul 2020 13:27:02 UTC
Severity: normal
Done: Mathieu Othacehe <othacehe <at> gnu.org>
Bug is archived. No further changes may be made.
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Your message dated Fri, 31 Jul 2020 13:04:47 +0200
with message-id <87r1ss0wts.fsf <at> gnu.org>
and subject line Re: [bug#42227] BPF in linux-libre
has caused the debbugs.gnu.org bug report #42227,
regarding BPF in linux-libre
to be marked as done.
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help-debbugs <at> gnu.org.)
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42227: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=42227
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Hey John,
> I think I tidied up the description to match the Guix situation. What do
> you think now?
Yes it's fine, thanks for the updated serie! I pushed the first patch
and patches two and three squashed together.
> I could see it being a useful default. BPF seems like a nice technology
> but I am making these patches to experiment with it myself. Because I
> haven't used it much I can't really speak on the pros of making it
> default. Other than my gut feeling that seems like something that
> should be opted into rather than opting out of I have no strong feelings
> on including it by default. The only other downside I see is that
> putting in the default might make the linux definitions less composable.
> The way it is now, one can assemble a (mostly) bpf-capable system from
> the pieces in gnu/packages/linux.scm.
Ok, thanks for explaining. I don't have much experience with BPF
either. For now we can work with a separate linux-libre, and will see
about merging it into the default, when we'll have more perspective.
I'll take more time to review patches 4 and 5. However, while trying
some of the examples packaged by BCC, I have the following error:
--8<---------------cut here---------------start------------->8---
mathieu <at> meru:~/guix-master$ /gnu/store/rv51f9n1w9i92m9qsg9k3ilsy3hyhjf3-bcc-0.15.0/share/bcc/tools/execsnoop
Traceback (most recent call last):
File "/gnu/store/rv51f9n1w9i92m9qsg9k3ilsy3hyhjf3-bcc-0.15.0/share/bcc/tools/execsnoop", line 21, in <module>
from bcc import BPF
ModuleNotFoundError: No module named 'bcc'
--8<---------------cut here---------------end--------------->8---
I think an additional wrapping is necessary. Could you please have a
look? I'm also removing help-guix, and opening a proper guix-patches
ticket.
Thanks,
Mathieu
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Hey,
> That seems ok. I did find a few questions about debugfs on old irc logs
> and mailing lists. My only concern again is that I would prefer to opt
> in to such a thing. debugfs is much simpler than the bpf kernel flags
> though, so maybe it will be ok to remove in the future.
Yeah, but I saw that Ubuntu for instance is enabling it by default, so I
guess it could help to have the same behaviour in Guix System. Added it
with: 6bb07e91e1ab9367f636a3a5e9d52a9e0772aa89.
> But I cannot see anything guix does differently that would cause it to
> fail. My only feeling is perhaps our configure flags for binutils might
> be causing the issue.
>
> As is, however, bpftrace does work even with out HAVE_BFD_DISASM and I
> even used it to debug a few processes recently.
Gave it another try and I think if we could get "binutils" to produce a
dynamic version of libbfd.a, that would make the trick. Anyway, let's
proceed without BFD support for now. Pushed bpftrace as
c55acb073248392b1387017378f36a1d378fa7c4.
Closing the serie, thank you!
Mathieu
This bug report was last modified 4 years and 298 days ago.
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