[PATCH] kbuild: buildtar: add comments about inconsistent package generation

[Emil Renner Berthing]

Masahiro Yamada wrote:
> scripts/package/buildtar checks some kernel packages, and copies the
> first image found. This may potentially produce an inconsistent (and
> possibly wrong) package.
>
> For instance, the for-loop for arm64 checks Image.{bz2,gz,lz4,lzma,lzo},
> and vmlinuz.efi, then copies the first image found, which might be a
> stale image.
>
> When CONFIG_EFI_ZBOOT is enabled in the pristine source tree,
> 'make ARCH=arm64 tar-pkg' will build and copy vmlinuz.efi. This is the
> expected behavior.
>
> If you build the kernel with CONFIG_EFI_ZBOOT, Image.gz will be created,
> which will remain in the build directory unless you clean it. Even if
> CONFIG_EFI_ZBOOT is turned on later, 'make ARCH=arm64 tar-pkg' will copy
> stale Image.gz instead of the latest vmlinuz.efi, as Image.gz takes
> precedence over vmlinuz.efi.
>
> In summary, the code "[ -f ... ] && cp" does not consistently produce
> the desired outcome.
>
> The other package scripts are deterministic; scripts/package/mkdebian,
> for example, chooses a copied kernel image based on CONFIG options.
>
> I removed [ -f ... ] checks from x86, alpha, parisc, and the default
> because they have a single kernel image to copy. If it is missing, it
> should be an error.
>
> I did not modify the code for mips, arm64, riscv. Instead, I left some
> comments. Eventually, someone may fix the code, or at the very least,
> it may discourage the copy-pasting of incorrect code.
>
> Signed-off-by: Masahiro Yamada <masahiroy at kernel.org>

Hi Masahiro,

Thanks for the patch. I wonder why arm64 and riscv is not just using
KBUILD_IMAGE as the source path of the image to copy like some other
architectures do. In any case:

Reviewed-by: Emil Renner Berthing <emil.renner.berthing at canonical.com>

> ---
>
>  scripts/package/buildtar | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/scripts/package/buildtar b/scripts/package/buildtar
> index 72c91a1b832f..ed8d9b496305 100755
> --- a/scripts/package/buildtar
> +++ b/scripts/package/buildtar
> @@ -53,18 +53,24 @@ cp -v -- "${objtree}/vmlinux" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
>  #
>  # Install arch-specific kernel image(s)
>  #
> +# Note:
> +#   mips, arm64, and riscv copy the first image found. This may not produce
> +#   the desired outcome because it may pick up a stale file remaining in the
> +#   build tree.
> +#
>  case "${ARCH}" in
>  	x86|i386|x86_64)
> -		[ -f "${objtree}/arch/x86/boot/bzImage" ] && cp -v -- "${objtree}/arch/x86/boot/bzImage" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
> +		cp -v -- "${objtree}/arch/x86/boot/bzImage" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
>  		;;
>  	alpha)
> -		[ -f "${objtree}/arch/alpha/boot/vmlinux.gz" ] && cp -v -- "${objtree}/arch/alpha/boot/vmlinux.gz" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
> +		cp -v -- "${objtree}/arch/alpha/boot/vmlinux.gz" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
>  		;;
>  	parisc*)
> -		[ -f "${KBUILD_IMAGE}" ] && cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
> +		cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
>  		[ -f "${objtree}/lifimage" ] && cp -v -- "${objtree}/lifimage" "${tmpdir}/boot/lifimage-${KERNELRELEASE}"
>  		;;
>  	mips)
> +		# Please note the following code may copy a stale file.
>  		if [ -f "${objtree}/arch/mips/boot/compressed/vmlinux.bin" ]; then
>  			cp -v -- "${objtree}/arch/mips/boot/compressed/vmlinux.bin" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
>  		elif [ -f "${objtree}/arch/mips/boot/compressed/vmlinux.ecoff" ]; then
> @@ -86,6 +92,7 @@ case "${ARCH}" in
>  		fi
>  		;;
>  	arm64)
> +		# Please note the following code may copy a stale file.
>  		for i in Image.bz2 Image.gz Image.lz4 Image.lzma Image.lzo vmlinuz.efi ; do
>  			if [ -f "${objtree}/arch/arm64/boot/${i}" ] ; then
>  				cp -v -- "${objtree}/arch/arm64/boot/${i}" "${tmpdir}/boot/vmlinuz-${KERNELRELEASE}"
> @@ -94,6 +101,7 @@ case "${ARCH}" in
>  		done
>  		;;
>  	riscv)
> +		# Please note the following code may copy a stale file.
>  		for i in Image.bz2 Image.gz Image; do
>  			if [ -f "${objtree}/arch/riscv/boot/${i}" ] ; then
>  				cp -v -- "${objtree}/arch/riscv/boot/${i}" "${tmpdir}/boot/vmlinux-${KERNELRELEASE}"
> @@ -102,7 +110,7 @@ case "${ARCH}" in
>  		done
>  		;;
>  	*)
> -		[ -f "${KBUILD_IMAGE}" ] && cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinux-kbuild-${KERNELRELEASE}"
> +		cp -v -- "${KBUILD_IMAGE}" "${tmpdir}/boot/vmlinux-kbuild-${KERNELRELEASE}"
>  		echo "" >&2
>  		echo '** ** **  WARNING  ** ** **' >&2
>  		echo "" >&2
> --
> 2.40.1
>
>
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