[Pkg-zfsonlinux-devel] Bug#1025171: Bug#1025171: zfs-dkms FTBFS against 6.0.0-5-amd64

[M. Zhou]

Control: reassign -1 dkms 3.0.8-2
Control: retitle -1 regression: dkms/3.0.8-2 renders zfs-dkms FTBFS
Control: severity -1 serious

Hi,

Thank you for the information! I can confirm that this is the same issue
that you have encountered. By commenting out the --environment-overrides,
the current zfs-dkms package can be built against 6.0.0-5-amd64 successfully.

According to the build log when I filed the bug report, the problem is indeed
that the compiler cannot find the header files. I believed it was some -I ...
flags missing due to some reason.

So it is a regression bug in dkms/3.0.8-2, as -I flags needed for zfs-dkms
are accidentally removed.

On Wed, 2022-11-30 at 22:56 +0000, Heikki Kallasjoki wrote:
> There isn't enough detail to be sure, but this might be the same issue I
> hit on sid yesterday, so adding it here. It might also count as a dkms
> bug for all I know.
> 
> In my case, zfs-dkms fails to build against either of my currently
> installed kernels (5.19.0-1-amd64, 6.0.0-5-amd64), but only after
> updating the package dkms to version 3.0.8-2 (from 3.0.8-1).
> 
> This appears to be the result of the changes to the export-CC.patch:
> https://sources.debian.org/patches/dkms/3.0.8-2/export-CC.patch/
> 
> The 3.0.8-2 version adds the following commands to the prepare_build()
> function:
> 
>     export CC=$CC
>     export MAKEFLAGS="--environment-overrides"
> 
> I've verified that zfs-dkms builds fine for me if I temporarily comment
> out the second line from /usr/sbin/dkms.
> 
> A build log for a failed attempt (with the flag present) is at:
> https://0x0.st/o0fu.txt
> 
> The log also includes a dump of the environment variables at the start
> of the build, from a command I added to the dkms script.
> 
> Digging a little deeper, it appears that when `--environment-overrides`
> is set, a number of required command-line options (in particular, an -I
> option to add /var/lib/dkms/zfs/2.1.6/build/include in the include
> search path) fail to be set. I didn't manage to trace why exactly that
> is, but you can see both a failing and a working example (for one object
> file) at:
> https://0x0.st/o0EC.txt
> 
> FWIW, it seems like the build environment dkms uses inherits whatever
> was present in the environment when apt was called. If this is the case,
> then it feels to me including the `--environment-overrides` flag has
> potential to make things brittle. The effect of the flag is to: "Give
> variables taken from the environment precedence over variables from
> makefiles." Any arbitrary environment variables the user may have set
> for their own purposes might be unexpectedly overriding important
> variables from the Makefile(s).
> 
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