[Buildroot] [PATCHv2] package/zfs: Fix cross-platform-compilations

[Yann E. MORIN]

Romain, José, All,

On 2021-08-27 11:17 +0200, Romain Naour spake thusly:
> From: José Luis Salvador Rufo <salvador.joseluis at gmail.com>
> 
> This patch fixes the `make` executed from the `kernel.m4` in
> cross-platform-compilations environments:
> https://github.com/openzfs/zfs/blob/zfs-2.0.5/config/kernel.m4#L588
> 
> Fixes:
> https://gitlab.com/kubu93/buildroot/-/jobs/1522848483
> 
> Signed-off-by: José Luis Salvador Rufo <salvador.joseluis at gmail.com>
> Signed-off-by: Romain Naour <romain.naour at gmail.com>
> ---
> v2: add a patch to remove DESTDIR used with INSTALL_MOD_PATH
>     Use LINUX_MAKE_FLAGS for ZFS_MAKE_ENV and ZFS_CONF_ENV
>     http://lists.busybox.net/pipermail/buildroot/2021-August/621350.html

I've only had a cursory look at the previous discussion, sorry...

However, I believe this is incorrect to pass $(LINUX_MAKE_FLAGS) in the
environment for configure and make.

Indeed, $(LINUX_MAKE_FLAGS) should really only be used when actually
building kernel modules, not userland stuff, because it contains
variables that are not valid otherwise.

For example, it overrides HOSTCC with a value that is not correct
outside of bulding the kernel. It also conditionally contains the
unscoped variable LOADADDR, which name is too generic.

Also, I don't understand why we need these at configure time, because we
are using the kernel-module infra to build the kernel module... And
basically, the two are mostly mutually exclusive...

> ---
>  ...in-don-t-use-DESTDIR-and-INSTALL_MOD.patch | 44 +++++++++++++++++++
>  package/zfs/zfs.mk                            |  5 +++
>  2 files changed, 49 insertions(+)
>  create mode 100644 package/zfs/0001-module-Makefile.in-don-t-use-DESTDIR-and-INSTALL_MOD.patch
> 
> diff --git a/package/zfs/0001-module-Makefile.in-don-t-use-DESTDIR-and-INSTALL_MOD.patch b/package/zfs/0001-module-Makefile.in-don-t-use-DESTDIR-and-INSTALL_MOD.patch
> new file mode 100644
> index 0000000000..e1d0f91533
> --- /dev/null
> +++ b/package/zfs/0001-module-Makefile.in-don-t-use-DESTDIR-and-INSTALL_MOD.patch
> @@ -0,0 +1,44 @@
> +From 12851a8dbc0aeb8e48f21f1e0cb7b3123029594e Mon Sep 17 00:00:00 2001
> +From: Romain Naour <romain.naour at gmail.com>
> +Date: Thu, 26 Aug 2021 23:12:31 +0200
> +Subject: [PATCH] module/Makefile.in: don't use DESTDIR and INSTALL_MOD_PATH
> + together
> +
> +DESTDIR and INSTALL_MOD_PATH are usually set with absolute path
> +by build system (Buildroot), so when used together it concatenates
> +two absolute path.
> +
> +Keep INSTALL_MOD_PATH since it's set when building an out of tree
> +kernel module.
> +
> +Signed-off-by: Romain Naour <romain.naour at gmail.com>

That patch on its own is correct, though. It should be pushed upstream.

> +---
> + module/Makefile.in | 6 +++---
> + 1 file changed, 3 insertions(+), 3 deletions(-)
> +
> +diff --git a/module/Makefile.in b/module/Makefile.in
> +index 69caf4857..043f2bdea 100644
> +--- a/module/Makefile.in
> ++++ b/module/Makefile.in
> +@@ -76,15 +76,15 @@ clean: clean- at ac_system@
> + modules_install-Linux:
> + 	@# Install the kernel modules
> + 	$(MAKE) -C @LINUX_OBJ@ M=`pwd` modules_install \
> +-		INSTALL_MOD_PATH=$(DESTDIR)$(INSTALL_MOD_PATH) \
> ++		INSTALL_MOD_PATH=$(INSTALL_MOD_PATH) \
> + 		INSTALL_MOD_DIR=$(INSTALL_MOD_DIR) \
> + 		KERNELRELEASE=@LINUX_VERSION@
> + 	@# Remove extraneous build products when packaging
> +-	kmoddir=$(DESTDIR)$(INSTALL_MOD_PATH)/lib/modules/@LINUX_VERSION@; \
> ++	kmoddir=$(INSTALL_MOD_PATH)/lib/modules/@LINUX_VERSION@; \
> + 	if [ -n "$(DESTDIR)" ]; then \
> + 		find $$kmoddir -name 'modules.*' | xargs $(RM); \
> + 	fi
> +-	sysmap=$(DESTDIR)$(INSTALL_MOD_PATH)/boot/System.map- at LINUX_VERSION@; \
> ++	sysmap=$(INSTALL_MOD_PATH)/boot/System.map- at LINUX_VERSION@; \
> + 	if [ -f $$sysmap ]; then \
> + 		depmod -ae -F $$sysmap @LINUX_VERSION@; \
> + 	fi
> +-- 
> +2.31.1
> +
> diff --git a/package/zfs/zfs.mk b/package/zfs/zfs.mk
> index 3b1afb419a..537d4ece15 100644
> --- a/package/zfs/zfs.mk
> +++ b/package/zfs/zfs.mk
> @@ -13,6 +13,11 @@ ZFS_CPE_ID_PRODUCT = openzfs
>  
>  ZFS_AUTORECONF = YES
>  
> +# cross compile environment for linux kernel module
> +ZFS_MAKE_ENV = $(LINUX_MAKE_FLAGS)
> +# `./configure` will execute a `make modules` test case
> +ZFS_CONF_ENV = $(LINUX_MAKE_FLAGS)

This hunk I am not too happy about... :-/

Regards,
Yann E. MORIN.

>  ZFS_DEPENDENCIES = libaio openssl udev util-linux zlib
>  
>  # sysvinit installs only a commented-out modules-load.d/ config file
> -- 
> 2.31.1
> 
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