[Buildroot] [PATCH v3 3/7] fs/iso9660: add support to Grub EFI bootloader in the image

[Yann E. MORIN]

Köry, All,

On 2021-09-23 17:57 +0200, Kory Maincent spake thusly:
> Add support to boot the Grub bootloader from an EFI BIOS in the ISO9660
> image.
> For that we need to create EFI System Partition (ESP). The ESP is a vfat
> partition which contain the Grub2 binary at the /EFI/BOOT/ location.
> xorriso command will generate the iso image including the ESP.
> 
> We notice Grub can not read and mount the ESP, therefore we place the Grub
> configuration file in the ISO9660 partition. A Grub2 builtin configuration
> need to be used to tell Grub2 to search automatically its configuration
> file in the ISO9660 partition. Use 'set root=(cd0)' in the configuration
> file passed to BR2_TARGET_GRUB2_BUILTIN_CONFIG_EFI.
> 
> Signed-off-by: Kory Maincent <kory.maincent at bootlin.com>
> ---
[--SNIP--]
> diff --git a/fs/iso9660/iso9660.mk b/fs/iso9660/iso9660.mk
> index 23421a9a5c..921efa1b02 100644
> --- a/fs/iso9660/iso9660.mk
> +++ b/fs/iso9660/iso9660.mk
> @@ -57,7 +57,12 @@ else
>  ROOTFS_ISO9660_TMP_TARGET_DIR = $(TARGET_DIR)
>  endif
>  
> -ifeq ($(BR2_TARGET_ROOTFS_ISO9660_GRUB2),y)
> +ifeq ($(BR2_REPRODUCIBLE),y)
> +ROOTFS_ISO9660_VFAT_OPTS = --invariant
> +ROOTFS_ISO9660_FIX_TIME = touch $(SOURCE_DATE_EPOCH)

I think you may have missed something about SOURCE_DATE_EPOCH: it is a
UNIX timestamp, as a number of seconds elapsed since 1970-01-01T00:00:00+0000.
Right now, it's around 1632775187.

So, what you wrote would create a file named '1632775187' in the
Buildroot top-level directory... Probably not what is expected...

So I've changed to:

    ifeq ($(BR2_REPRODUCIBLE),y)
    ROOTFS_ISO9660_VFAT_OPTS = --invariant
    ROOTFS_ISO9660_FIX_TIME = touch -d @$(SOURCE_DATE_EPOCH)
    else
    ROOTFS_ISO9660_FIX_TIME = @:
    endif

... and then...

> +ifeq ($(BR2_TARGET_ROOTFS_ISO9660_GRUB2)$(BR2_TARGET_ROOTFS_ISO9660_BIOS_BOOTLOADER),yy)
>  ROOTFS_ISO9660_DEPENDENCIES += grub2
>  ROOTFS_ISO9660_BOOTLOADER_CONFIG_PATH = \
>  	$(ROOTFS_ISO9660_TMP_TARGET_DIR)/boot/grub/grub.cfg
> @@ -66,6 +71,22 @@ define ROOTFS_ISO9660_INSTALL_BOOTLOADER
>  	$(INSTALL) -D -m 0644 $(BINARIES_DIR)/grub-eltorito.img \
>  		$(ROOTFS_ISO9660_TMP_TARGET_DIR)/boot/grub/grub-eltorito.img
>  endef
> +else ifeq ($(BR2_TARGET_ROOTFS_ISO9660_GRUB2)$(BR2_TARGET_ROOTFS_ISO9660_EFI_BOOTLOADER),yy)
> +ROOTFS_ISO9660_DEPENDENCIES += grub2 host-dosfstools host-mtools
> +ROOTFS_ISO9660_EFI_PARTITION = boot/fat.efi
> +ROOTFS_ISO9660_EFI_PARTITION_PATH = $(ROOTFS_ISO9660_TMP_TARGET_DIR)/$(ROOTFS_ISO9660_EFI_PARTITION)
> +ROOTFS_ISO9660_EFI_PARTITION_CONTENT = $(BINARIES_DIR)/efi-part
> +ROOTFS_ISO9660_BOOTLOADER_CONFIG_PATH = \
> +	$(ROOTFS_ISO9660_TMP_TARGET_DIR)/boot/grub/grub.cfg
> +define ROOTFS_ISO9660_INSTALL_BOOTLOADER
> +	rm -rf $(ROOTFS_ISO9660_EFI_PARTITION_PATH)
> +	mkdir -p $(dir $(ROOTFS_ISO9660_EFI_PARTITION_PATH))
> +	dd if=/dev/zero of=$(ROOTFS_ISO9660_EFI_PARTITION_PATH) bs=1M count=1
> +	$(ROOTFS_ISO9660_FIX_TIME)
> +	$(HOST_DIR)/sbin/mkfs.vfat $(ROOTFS_ISO9660_VFAT_OPTS) $(ROOTFS_ISO9660_EFI_PARTITION_PATH)

... here:

    $(ROOTFS_ISO9660_FIX_TIME) $(ROOTFS_ISO9660_EFI_PARTITION_CONTENT)/*

... and...

> +	$(HOST_DIR)/bin/mcopy -p -m -i $(ROOTFS_ISO9660_EFI_PARTITION_PATH) -s \
> +		$(ROOTFS_ISO9660_EFI_PARTITION_CONTENT)/* ::/

... here:

    $(ROOTFS_ISO9660_FIX_TIME) $(ROOTFS_ISO9660_EFI_PARTITION_PATH)

Applied to master with the above changes, thanks.

Regards,
Yann E. MORIN.

> +endef
>  else ifeq ($(BR2_TARGET_ROOTFS_ISO9660_ISOLINUX),y)
>  ROOTFS_ISO9660_DEPENDENCIES += syslinux
>  ROOTFS_ISO9660_BOOTLOADER_CONFIG_PATH = \
> @@ -128,9 +149,25 @@ ROOTFS_ISO9660_PRE_GEN_HOOKS += ROOTFS_ISO9660_DISABLE_EXTERNAL_INITRD
>  
>  endif # ROOTFS_ISO9660_USE_INITRD
>  
> +ROOTFS_ISO9660_OPTS += \
> +	-J \
> +	-R \
> +	-no-emul-boot
> +
> +ifeq ($(BR2_TARGET_ROOTFS_ISO9660_BIOS_BOOTLOADER),y)
> +ROOTFS_ISO9660_OPTS += \
> +	-boot-load-size 4 \
> +	-boot-info-table \
> +	-b $(ROOTFS_ISO9660_BOOT_IMAGE)
> +endif
> +
> +ifeq ($(BR2_TARGET_ROOTFS_ISO9660_EFI_BOOTLOADER),y)
> +ROOTFS_ISO9660_OPTS += \
> +	--efi-boot $(ROOTFS_ISO9660_EFI_PARTITION)
> +endif
> +
>  define ROOTFS_ISO9660_CMD
> -	$(HOST_DIR)/bin/xorriso -as mkisofs -J -R -b $(ROOTFS_ISO9660_BOOT_IMAGE) \
> -		-no-emul-boot -boot-load-size 4 -boot-info-table \
> +	$(HOST_DIR)/bin/xorriso -as mkisofs \
>  		$(ROOTFS_ISO9660_OPTS) \
>  		-o $@ $(ROOTFS_ISO9660_TMP_TARGET_DIR)
>  endef
> -- 
> 2.25.1
> 
> _______________________________________________
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> buildroot at lists.buildroot.org
> https://lists.buildroot.org/mailman/listinfo/buildroot

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