bug#45633: bcc and bpftrace require kernel headers from system

bug#45633: bcc and bpftrace require kernel headers from system

[John Soo]

Hi Guix,

When I added bcc and bpftrace to guix I didn't think much of which
version of the kernel headers would be used.  After a few kernel
updates, it has become clear that the current-system kernel headers need
to match the kernel headers the packages are compiled with.  Can they be
provided with a variant property?  The ocaml packages that need
different ocaml versions seem like a nice model on how to do the kernel
headers.

Thoughts?

 - John

bug#45633: bcc and bpftrace require kernel headers from system

[Tobias Geerinckx-Rice via Bug reports for GNU Guix]

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John,

This reminds me of <http://issues.guix.gnu.org/45592>.

John Soo 写道：
> Hi Guix,
>
> When I added bcc and bpftrace to guix I didn't think much of 
> which
> version of the kernel headers would be used.  After a few kernel
> updates, it has become clear that the current-system kernel 
> headers need

This should probably be booted-system.

> to match the kernel headers the packages are compiled with.  Can 
> they be
> provided with a variant property?  The ocaml packages that need
> different ocaml versions seem like a nice model on how to do the 
> kernel
> headers.

I know exact kernel headers are needed at toolchain run time, when 
building eBPF programmes.  Are they really needed at toolchain 
build time, too?  That sounds wrong (but there are more things 
fundamentally wrong with eBPF on Linux; ask me to rant about 
CONFIG_IKHEADERS).  Still, could pointing bcc/bpftrace to 
booted-system headers at run time not suffice?

Kind regards,

T G-R

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bug#45633: bcc and bpftrace require kernel headers from system

[John Soo]

Hi Tobias,

Tobias Geerinckx-Rice <me@tobias.gr> writes:

> John,
>
> This reminds me of <http://issues.guix.gnu.org/45592>.

Hm, maybe. How does it remind you of zfs? It seems like zfs needs the
libraries from util-linux, right? bcc and bpftrace need the kernel
headers. The following should illustrate there is nothing to load
dynamically, right?

find $(guix build linux-libre-headers) -name '*.\.so*'

> This should probably be booted-system.

Yes, definitely, thanks. s/current-system/booted-system/

> I know exact kernel headers are needed at toolchain run time, when
> building eBPF programmes.  Are they really needed at toolchain 
> build time, too?

I am not sure what the headers are used for but they are indeed the .h
files (tree $(guix build linux-libre-headers)).  I would assume they are
used by the gcc-toolchain when compiling the package as #includes.

What do you think?

- John