[OE-core] zimage Initramfs booting stuck at Start Kernel

[JH]

Hi Ferry,

On 10/27/19, Ferry Toth <fntoth at gmail.com> wrote:
> Op 27-10-2019 om 02:27 schreef JH:
>> Hi Ferry,
>>
>> On 10/27/19, Ferry Toth <fntoth at gmail.com> wrote:
>>>
>>> As an example you might want to look at my repo, I have 2 images minimal
>>> and initramfs:
>>> https://github.com/edison-fw/meta-intel-edison/tree/master/meta-intel-edison-distro/recipes-core/images
>>>
>>> I don't exactly know how you are doing it. But I'll try to explain what
>>> I do:
>>> I have
>>> 1) a normal rootfs (say edison-image-minimal) and
>>> 2) a initramfs rootfs containing kernel modules needed for booting and a
>>> init script.
>>>
>>> Initramfs is build using core-image-minimal-initramfs.bbappend. Some
>>> additional unneeded packages are pulled, and as size is restricted (10MB
>>> or so?) we remove them here.
>>
>> Thanks for the tips, that confirms my long suspensions that the size
>> of the image could be the cause of the problem, my working zImage size
>> is 8MB, my failing zImager-initramfs size is 35MB. How did you remove
>> the 10 MB size restriction? I checked your
>
> I don't. I reduce the contents as much as possible.

That is not practical, we cannot limit the kernel + rootfs to 10 MB size.

>> core-image-minimal-initramfs.bbappend, there is no sign to remove 10
>> MB size restriction. You have a resize-rootfs.service, but I am not
>> sure that is the one for fixing the 10 MB size restriction. The
>
> No, it isn't.
>
>> edison-image-minimal.bb has the IMAGE_ROOTFS_SIZE = "1048576", sorry
>> for my dumb, is that size for 1048576 KB (1GB) or 1048576 B (1MB)?
>
> The rootfs is on disk (/) and is 1GB. It has nothing to do with initramfs.

OK.

>>> The init script is here:
>>> https://github.com/edison-fw/meta-intel-edison/blob/master/meta-intel-edison-distro/recipes-core/initrdscripts/initramfs-framework/init
>>>
>>> The init script loads modules, waits for the disk with the rootfs to
>>> appear and mount it. Then switchroot to it.
>>> If it doesn't appear it drops to a shell so you can investigate what's
>>> wrong.
>>
>> I am confident that the 10 MB size restriction is the problem, I am
>> not clear where that 10 MB size restriction is defined and how to fix
>> the size restriction, appreciate your helps.
>
> I am not sure where it comes from, I think internal in the kernel there
> is a limit, after uncompress. Initramfs is in ram, I think we just need
> to accept there is a size restriction.

No, there is no limitation in kernel, BTW, the zImage-initramfs is not
just kernel space, the zImage-initramfs = kernel + rootfs which cannot
be limited to 10 MB. I have a zImage-initramfs created by openwrt, the
size is 28 MB. The problem is created by oe-core, most likely in
kernel.bbclass, could anyone in oe-core development provide insights
where is the 10 MB limitation from and how to fix it?

>>> To build everything edison-image-minimal triggers build of u-boot,
>>> kernel, rootfs, initramfs and kernel-with-built-in-initramfs.
>>
>>> Search for 'init' and 'live' and find the needed lines in
>>> https://github.com/edison-fw/meta-intel-edison/blob/master/meta-intel-edison-distro/recipes-core/images/edison-image-minimal.bb
>>
>> I looked at the init script, but not clear if it is critical for
>> fixing that issue or not. My init is the symblic link to
>> /lib/systemd/systemd in imx6.
>
> Given the size restriction I think we have no choice to use initramfs to
> load minimum required modules and then mount and switchroot to a file
> system on disk. So, yes, you need to modify init for that. After
> switchroot there will be a new init, the symbolic link you mention.

That is not good, we need to fix it. I am still new to oe-core,
bitbake and Yocto, but I am happy to give a try if someone could point
me where could be the source for the 10 MB limitation of
zImage-initramfs.

Thank you very much.

Kind regards,

- jh