Re: [Buildroot] [PATCH next v5 2/3] fs/cpio: new option to use dracut tool

From: "Yann E. MORIN" <yann.morin.1998@free.fr>
To: "Arnout Vandecappelle (Essensium/Mind)" <arnout@mind.be>
Cc: Adam Duskett <aduskett@gmail.com>,
	Thierry Bultel <thierry.bultel@linatsea.fr>,
	buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH next v5 2/3] fs/cpio: new option to use dracut tool
Date: Mon, 15 Aug 2022 15:05:13 +0200	[thread overview]
Message-ID: <20220815130513.GX2854108@scaer> (raw)
In-Reply-To: <20220815111710.1459820-2-arnout@mind.be>

Arnout, All,

On 2022-08-15 13:17 +0200, Arnout Vandecappelle (Essensium/Mind) spake thusly:
> From: Thierry Bultel <thierry.bultel@linatsea.fr>
> 
> Adds an option to invoke the dracut host tool, providing
> a configuration file, instead of having a full cpio archive
> of the whole target directory.
[--SNIP--]
> diff --git a/fs/cpio/Config.in b/fs/cpio/Config.in
> index c1151a2881..de83aaad65 100644
> --- a/fs/cpio/Config.in
> +++ b/fs/cpio/Config.in
> @@ -7,6 +7,40 @@ config BR2_TARGET_ROOTFS_CPIO
>  
>  if BR2_TARGET_ROOTFS_CPIO
>  
> +choice
> +	prompt "cpio type"
> +	default BR2_TARGET_ROOTFS_CPIO_FULL
> +
> +config BR2_TARGET_ROOTFS_CPIO_FULL
> +	bool "cpio the whole root filesystem"
> +	help
> +	  Build a cpio archive containing the whole the root filesystem.
> +
> +config BR2_TARGET_ROOTFS_CPIO_DRACUT
> +	bool "Invoke dracut to make a partial initramfs"
> +	select BR2_PACKAGE_HOST_DRACUT
> +	select BR2_PACKAGE_HOST_UBOOT_TOOLS

As seen on IRC, host-uboot-tools are not required just for dracut.

> +if BR2_TARGET_ROOTFS_CPIO_DRACUT

Empty line after an 'if'...

> +config BR2_TARGET_ROOTFS_CPIO_DRACUT_CONF_FILE
> +	string "dracut configuration file"
> +	default "fs/cpio/dracut.conf"
> +	help
> +	  Dracut configuration file. It determines which parts of the
> +	  rootfs get included in the cpio image. See dracut.conf(5) or
> +	  https://github.com/dracutdevs/dracut/blob/master/man/dracut.conf.5.asc
> +
> +	  The default configuration file is suitable for busybox init.
> +	  It doesn't, however, pivot_root into a full rootfs.

... and before an 'endif'.

> +endif
> +
>  choice
>  	prompt "Compression method"
>  	default BR2_TARGET_ROOTFS_CPIO_NONE
> diff --git a/fs/cpio/cpio.mk b/fs/cpio/cpio.mk
> index 81f8c393d1..b62d804ad8 100644
> --- a/fs/cpio/cpio.mk
> +++ b/fs/cpio/cpio.mk
> @@ -36,6 +36,8 @@ ROOTFS_CPIO_DEPENDENCIES += host-cpio
>  ROOTFS_CPIO_OPTS += --reproducible
>  endif
>  
> +ifeq ($(BR2_TARGET_ROOTFS_CPIO_FULL),y)
> +
>  define ROOTFS_CPIO_CMD

We customarily do not define the _CMD (or _CMDS) conditionally. Instead,
we define conditional macros, and we expand them all in an unconditional
_CMD (or _CMDS) macro.

>  	cd $(TARGET_DIR) && \
>  	find . \
> @@ -44,6 +46,37 @@ define ROOTFS_CPIO_CMD
>  	> $@
>  endef
>  
> +else ifeq ($(BR2_TARGET_ROOTFS_CPIO_DRACUT),y)
> +
> +ROOTFS_CPIO_DEPENDENCIES += host-dracut
> +
> +ifeq ($(BR_BUILDING):$(BR2_TARGET_ROOTFS_CPIO_DRACUT_CONF_FILE),y:)
> +$(error No dracut config file name specified, check your BR2_TARGET_ROOTFS_CPIO_DRACUT_CONF_FILE setting)
> +endif
> +
> +ifeq ($(BR2_LINUX_KERNEL),y)
> +ROOTFS_CPIO_DEPENDENCIES += linux
> +ROOTFS_CPIO_OPTS += --kver $(LINUX_VERSION_PROBED)
> +else
> +ROOTFS_CPIO_OPTS += --no-kernel
> +endif
> +
> +define ROOTFS_CPIO_CMD
> +	mkdir -p $(ROOTFS_CPIO_DIR)/tmp
> +
> +	$(HOST_DIR)/bin/dracut \
> +		$(ROOTFS_CPIO_OPTS) \
> +		-c $(BR2_TARGET_ROOTFS_CPIO_DRACUT_CONF_FILE) \
> +		--sysroot $(TARGET_DIR) \

Hrmm.. --sysroot is misleading in our situation. Also, it can be spelt
-r so our wrapper must also cope with it (in case it is called from a
post-image script).

[--SNIP--]
> diff --git a/fs/cpio/dracut.conf b/fs/cpio/dracut.conf
> new file mode 100644
> index 0000000000..6184457723
> --- /dev/null
> +++ b/fs/cpio/dracut.conf
> @@ -0,0 +1,93 @@
[--SNIP--]
> +"
> +

Spurious emoty line at EOF.

Regards,
Yann E. MORIN.

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