[Buildroot] [PATCH 3/3] package/systemd: generate hwdb.bin

[Carlos Santos]

On Mon, Oct 28, 2019 at 7:54 PM Yann E. MORIN <yann.morin.1998 at free.fr> wrote:
>
> For the hwdb installed by systemd to be useful, it has to be compiled
> into a binary form.
>
> This is a bit tricky:
>   - the .hwdb files (the source) are installed in TARGET_DIR,
>   - HOST_DIR/bin/udevadm only looks in HOST_DIR
>
> So, we copy the .hwdb files for the target from TARGET_DIR and into
> HOST_DIR, run udevadm, and copy the generated hwdb.bin back to
> TARGET_DIR.
>
> Various packages may install their .hwdb files, so we can only generate
> hwdb.bin after all packages have been installed, that is as a
> target-finalize hook.
>
> Finally, the .hwdb files take as much space as the generated hwdb.bin
> (in the order of 8MiB currently), so we remove them for target.
>
> However, to still support iterative builds (e.g. make foo-reinstall), we
> still want to have the .hwdb in target/. So we remove them as a
> pre-rootfs hook.
>
> Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
> Cc: Peter Korsgaard <peter at korsgaard.com>
> Cc: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> Cc: Carlos Santos <unixmania at gmail.com>
> ---
>  package/systemd/Config.in  |  1 +
>  package/systemd/systemd.mk | 23 +++++++++++++++++++++++
>  2 files changed, 24 insertions(+)
>
> diff --git a/package/systemd/Config.in b/package/systemd/Config.in
> index 601398bf96..aef39abe27 100644
> --- a/package/systemd/Config.in
> +++ b/package/systemd/Config.in
> @@ -199,6 +199,7 @@ config BR2_PACKAGE_SYSTEMD_HOSTNAMED
>  config BR2_PACKAGE_SYSTEMD_HWDB
>         bool "enable hwdb installation"
>         default y
> +       select BR2_PACKAGE_HOST_EUDEV # for udevadm, during target-finalize
>         help
>           Enables hardware database installation to /usr/lib/udev/hwdb.d
>
> diff --git a/package/systemd/systemd.mk b/package/systemd/systemd.mk
> index df40961fee..4e8db8fd31 100644
> --- a/package/systemd/systemd.mk
> +++ b/package/systemd/systemd.mk
> @@ -203,6 +203,29 @@ endif
>
>  ifeq ($(BR2_PACKAGE_SYSTEMD_HWDB),y)
>  SYSTEMD_CONF_OPTS += -Dhwdb=true
> +
> +# "udevadm hwdb" was configured with its prefix set to HOST_DIR (it is
> +# from a host package), so it can only look in there to find .hwdb files.
> +# Remove existing .hwdb files (they are from the host variant or a
> +# previous run), and replace them with those from target.
> +# Note that systemd and eudev put their files in diffeernt locations.
> +define SYSTEMD_BUILD_HWDB
> +       rm -rf $(HOST_DIR)/etc/udev/hwdb.d
> +       cp -a $(TARGET_DIR)/usr/lib/udev/hwdb.d $(HOST_DIR)/etc/udev/hwdb.d
> +       $(HOST_DIR)/bin/udevadm hwdb --update
> +       $(INSTALL) -D -m 0644 $(HOST_DIR)/etc/udev/hwdb.bin \
> +               $(TARGET_DIR)/usr/lib/udev/hwdb.bin

Use

        $(HOST_DIR)/bin/udevadm hwdb --update --root $(TARGET_DIR)

> +endef
> +SYSTEMD_TARGET_FINALIZE_HOOKS += SYSTEMD_BUILD_HWDB
> +
> +# Note: this will run in the filesystem context, so will use a copy
> +# of tharget/, not the real one, so the files are still available on
> +# re-builds (foo-rebuild, etc...)
> +define SYSTEMD_RM_HWDB_SRC
> +       rm -rf $(TARGET_DIR)/usr/lib/udev/hwdb.d/
> +endef
> +SYSTEMD_ROOTFS_PRE_CMD_HOOKS += SYSTEMD_RM_HWDB_SRC
> +
>  else
>  SYSTEMD_CONF_OPTS += -Dhwdb=false
>  endif
> --
> 2.20.1
>


-- 
Carlos Santos <unixmania at gmail.com>