[OpenWrt-Devel] [PATCH 07/11] include/image.mk: add support for building a dm-verity enabled squashfs image

[Thomas Petazzoni]

Hello Hauke,

One again, thanks for the review!

On Mon, 25 Mar 2019 18:21:56 +0100
Hauke Mehrtens <hauke at hauke-m.de> wrote:

> >  fs-types-$(CONFIG_TARGET_ROOTFS_SQUASHFS) += squashfs
> > +fs-types-$(CONFIG_TARGET_ROOTFS_SQUASHFS_HASHED) += squashfs-hashed
> >  fs-types-$(CONFIG_TARGET_ROOTFS_JFFS2) += $(addprefix jffs2-,$(JFFS2_BLOCKSIZE))
> >  fs-types-$(CONFIG_TARGET_ROOTFS_JFFS2_NAND) += $(addprefix jffs2-nand-,$(NAND_BLOCKSIZE))
> >  fs-types-$(CONFIG_TARGET_ROOTFS_EXT4FS) += ext4
> > @@ -207,6 +208,17 @@ define Image/mkfs/squashfs
> >  		$(if $(SOURCE_DATE_EPOCH),-fixed-time $(SOURCE_DATE_EPOCH))
> >  endef
> >  
> > +define Image/mkfs/squashfs-hashed
> > +	$(STAGING_DIR_HOST)/bin/mksquashfs4 $(call mkfs_target_dir,$(1)) $@ \  
> 
> Why don't you just call Image/mkfs/squashfs here and then do the
> additional veritysetup?

Because Image/mkfs/squashfs passes the -nopad option, causing the image
to not be 4 KB-padded, while "veritysetup format" needs a 4KB-padded
image, which is what mksquashfs does by default when -nopad is *not*
passed. An alternate solution is to use Image/mkfs/squashfs, and then
pad the image separately.

> > +		-noappend -root-owned \
> > +		-comp $(SQUASHFSCOMP) $(SQUASHFSOPT) \
> > +		-processors 1 \
> > +		$(if $(SOURCE_DATE_EPOCH),-fixed-time $(SOURCE_DATE_EPOCH))  
> 
> Setting SOURCE_DATE_EPOCH is not needed any more.

Ah, indeed, it has been dropped from Image/mkfs/squashfs. Allowed me to
discover the squashfskit fork of squashfs-tools, which I wasn't aware
of.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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