Re: [PATCH] tests/docker: Kludge <linux/swab.h> breakage by pinning linux-libc-dev

[Alex Bennée]

Philippe Mathieu-Daudé <address@hidden> writes:

> Linux kernel commit d5767057c9a [1] aimed to fix an issue with the
> swab() declaration, but doing so it introduced the BITS_PER_LONG
> definition, without using the kernel __ prefix, leading to odd
> failures in userland code using kernel uapi headers, such:
>
>       CC      block/file-posix.o
>     In file included from include/qemu/timer.h:4,
>                      from include/qemu/timed-average.h:29,
>                      from include/block/accounting.h:28,
>                      from include/block/block_int.h:27,
>                      from block/file-posix.c:30:
>     /usr/include/linux/swab.h: In function `__swab':
>     include/qemu/bitops.h:20:34: error: "sizeof" is not defined, evaluates to 
> 0 [-Werror=undef]
>        20 | #define BITS_PER_LONG           (sizeof (unsigned long) * 
> BITS_PER_BYTE)
>           |                                  ^~~~~~
>     include/qemu/bitops.h:20:41: error: missing binary operator before token 
> "("
>        20 | #define BITS_PER_LONG           (sizeof (unsigned long) * 
> BITS_PER_BYTE)
>           |                                         ^
>     cc1: all warnings being treated as errors
>     make: *** [rules.mak:69: block/file-posix.o] Error 1
>
> The issue has been fixed in Linux kernel commit 467d12f5c78 [2].
> Some distributions already backported the first commit, but still
> lack the second one.
>
> This is the case for Debian Buster.
> The linux-libc-dev package contains the Linux kernel headers.
> Kernel commit d5767057c9a has been backported in package
> commit 1fb0eb7956 "Update to 4.19.116" [3], see debian/changelog:
>
>   +linux (4.19.116-1) UNRELEASED; urgency=medium
>   ...
>   +    - uapi: rename ext2_swab() to swab() and share globally in swab.h
>
> The previous released update before it is debian/4.19.98-1,
> released as debian/4.19.98-1+deb10u1.
>
> We can find this package in the Debian snapshot archives,
> luckily archived on 2020-04-28 21:20:54 (see [4]).
>
> QEMU use Debian based Docker images for most of its cross-builds,
> which are tested by our Shippable CI jobs. The current broken
> package makes most of our CI red. We can kludge this by using the
> latest package released before the breakage. Do so by pinning
> the package version (apt hold), and using the snapshot archives,
> similar to commit b4048a7cd1.
> We'll revert once the fix is backported on Debian.

May as well mention:

  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=960271

>
> Reference to commits:
> [1] 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5767057c9a
> [2] 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=467d12f5c78
> [3] https://salsa.debian.org/kernel-team/linux/-/commit/1fb0eb7956
> [4] 
> http://snapshot.debian.org/package/linux/4.19.98-1%2Bdeb10u1/#linux-libc-dev_4.19.98-1:2b:deb10u1
>
> Cc: Salvatore Bonaccorso <address@hidden>
> Cc: Christian Borntraeger <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> Shippable green again:
> https://app.shippable.com/github/philmd/qemu/runs/759/summary/console
> ---
>  tests/docker/dockerfiles/debian10.docker | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/tests/docker/dockerfiles/debian10.docker 
> b/tests/docker/dockerfiles/debian10.docker
> index 0769700a41..d7084ac283 100644
> --- a/tests/docker/dockerfiles/debian10.docker
> +++ b/tests/docker/dockerfiles/debian10.docker
> @@ -9,6 +9,15 @@
>  #
>  FROM debian:buster-slim
>  
> + # Use a snapshot known to work (see http://snapshot.debian.org/#Usage)
> +ENV DEBIAN_SNAPSHOT_DATE "20200428T212054Z"
> +RUN sed -i \
> +    "s%^deb \(https\?://\)deb.debian.org/debian/\? \(.*\)%deb 
> [check-valid-until=no] 
> \1snapshot.debian.org/archive/debian/${DEBIAN_SNAPSHOT_DATE} \2%" \
> +    /etc/apt/sources.list
> +RUN sed -i \
> +    "s%^deb \(https\?://\)security.debian.org/debian-security/\? \(.*\)%deb 
> [check-valid-until=no] 
> \1snapshot.debian.org/archive/debian-security/${DEBIAN_SNAPSHOT_DATE} \2%" \
> +    /etc/apt/sources.list
> +
>  # Duplicate deb line as deb-src
>  RUN cat /etc/apt/sources.list | sed "s/^deb\ /deb-src /" >> 
> /etc/apt/sources.list
>  
> @@ -35,4 +44,11 @@ RUN apt update && \
>          texinfo \
>          $(apt-get -s build-dep qemu | egrep ^Inst | fgrep '[all]' | cut -d\  
> -f2)
>  
> +# Install common build utilities
> +RUN apt update && \
> +    DEBIAN_FRONTEND=noninteractive eatmydata \
> +    apt install -y --allow-downgrades \
> +        linux-libc-dev=4.19.98-1+deb10u1 && \
> +    apt-mark hold linux-libc-dev
> +

Do we need this bit? Surely if we have a snapshot URL we don't need to
hold the package as it will never get updated?

>  ENV FEATURES docs


-- 
Alex Bennée