[yocto] struggling with initramfs

[Andre McCurdy]

On Wed, Jul 4, 2018 at 11:23 PM, Zoran Stojsavljevic
<zoran.stojsavljevic at gmail.com> wrote:
> Hello to all,
>
> I have my own YOCTO recipe how I do the initramfs.
>
> Usually, some of these are missing in kernel .config file:
>
> CONFIG_BLK_DEV_INITRD=y
> CONFIG_RD_GZIP=y
> CONFIG_RD_BZIP2=y
> CONFIG_RD_LZMA=y
> CONFIG_RD_XZ=y
> CONFIG_RD_LZO=y
> CONFIG_RD_LZ4=y
>
> Please, check (they should be on) the CONFIG_DECOMPRESS_* options and if
> not, please, turn them on.
>
> To do this, please, for YOCTO use the following (to reconfigure kernel
> .config):
> bitbake -c menuconfig virtual/kernel
>
> Also, in the local.conf I have the following set:
>
> DISTRO_FEATURES_append = " ram"

There is no standard distro feature called "ram". Perhaps this is
something specific to your BSP layer?

> IMAGE_FSTYPES_append = " cpio.xz"
>
> Then I do: bitbake -k core-image-minimal, and from:
> .../build/tmp/tmp/deploy/images/<platform_name>
>
> Take my <initramfs_name>.cpio.xz as initramfs. Also, I take accordingly
> zImage and .dtb files as well.
>
> I prepend to initramfs.cpio.xz u-boot header:
> mkimage -n 'Ramdisk Image'  -A arm -O linux -T ramdisk -C gzip -d
> initramfs.cpio.xz initramfs.cpio.xz.uboot
>
> And then write tiny U-Boot ash script to tftp (from host) all three files to
> the target platform.

This advice and these instructions are all fine. However, just for the
record, creating a standalone cpio archive and arranging for the
bootloader to load the kernel and cpio archive into DRAM as separate
images before booting the kernel is not solving the same problem as
embedding a cpio archive inside the kernel image via OE's
INITRAMFS_IMAGE_BUNDLE option.

> On Wed, Jul 4, 2018 at 8:57 PM, Ferry Toth <ftoth at telfort.nl> wrote:
>>
>> Tim Hammer wrote:
>>
>> > Can anyone point me to a step-by-step tutorial or simple how-to on
>> > creating and using an initramfs with my kernel for ARM aarch64?
>> >
>> >
>> > I have tried creating my own:
>> >  - boot-image.bb file with IMAGE_FSTYPES = "cpio.gz".
>> >  - local.conf has INITRAMFS_IMAGE_BUNDLE = "1"
>> >  - linux.bbappend has INITRAMFS_IMAGE = "boot-image"
>> >
>> > This all seems to be "correct" to the extent that bitbake linux tries to
>> > do the right thing.
>> >
>> > However, I get a failure in do_bundle_initramfs- "mv: cannot stat
>> > 'arch/arm64/boot/Image': No such file or directory".
>> >
>> > To the best of my (limited) debugging abilities with Yocto, it seems
>> > like
>> > the kernel image backup has already been run when it gets to this point
>> > and the Image file in that directory has already been moved to
>> > Image.bak.
>> > If I comment out the mv statement in kernel.bbclass causing the failure,
>> > the process continues, but the initramfs does not seem to get populated
>> > or
>> > perhaps installed into my kernel image as I get kernel panics that I
>> > have
>> > been unable to get past.
>> >
>> >
>> > I decided to take a different approach and try using the
>> > core-image-minimal-initramfs recipe as INITRAMFS_IMAGE. By commenting
>> > out
>> > the COMPATIBLE_HOST entry I am able to build a kernel for ARM aarch64. I
>> > can even seem to boot into this initramfs- it counts down waiting for
>> > removable media; seems to find my primary rootfs on sda3, but there is
>> > no
>> > rootfs.img file there so says it is dropping to a shell (although I
>> > never
>> > get a prompt...).
>>
>> We have taken this approach here
>>
>> https://github.com/edison-fw/meta-intel-edison/tree/master/meta-intel-edison-distro/recipes-core
>>
>> There are 2 images, the rootfs and the initramfs. And we overload the
>> init-live.sh
>> to load certain kernel modules and acpi-tables then switchroot to the
>> rootfs.
>>
>> > Thinking I could start with that recipe and work to get rid of the live
>> > stuff and just get to a busybox prompt before trying to run my unique
>> > init
>> > commands, I copied  core-image-minimal-initramfs.bb to my-
>> > core-image-minimal-initramfs.bb in my layer and changed INITRAMFS_IMAGE
>> > to
>> > "my- core-image-minimal-initramfs".
>> > However, I obviously missed something in the configuration as I get an
>> > error in go_bundle_initramfs again:
>> >      kernel-source/scripts/gen_initramfs_list.sh:
>> >                  Cannot open
>> >
>> > '/.../linux-qoriq/4.14-r0/build/usr/my-core-image-minimal-initramfs-{machine}.cpio'
>> >
>> > Any help would be greatly appreciated.
>> > Thank you!
>>
>>
>> --
>> _______________________________________________
>> yocto mailing list
>> yocto at yoctoproject.org
>> https://lists.yoctoproject.org/listinfo/yocto
>
>