Re: [DistroKit] [PATCH 3/5] v8a: images: generate sparse images from rock3a initramfs, kernel and dtb

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 06.06.23 17:26, Ahmad Fatoum wrote:
> On 06.06.23 17:04, Johannes Zink wrote:
>> On 6/6/23 16:51, Ahmad Fatoum wrote:
>>> On 06.06.23 16:47, Johannes Zink wrote:
>>> Can you describe how to reproduce this with a normal DistroKit build?
>>
>> sure, just apply this series (or at least patch 1/5 for initrd generation), run ptxdist images and expose a fastboot partition on the DUT by calling
>>
>> usbgadget -A /tmp/initramfs(initramfs)c
>>
>> then use fastboot to upload the cpio.gz from your distrokit build dir
>>
>> fastboot flash initramfs platform-v8a/images/initramfs-sparse.img
> 
> I can reproduce this with fastboot version 28.0.2-debian.
> It wasn't always like that. I assume -S 0 wasn't always the
> default, but I haven't checked the code. I think it's worth a bug
> report.

I gave this a try and I am not so sure anymore this is a bug. Small images
are uploaded without problem. This cut off seems to be 8M.

Above 8M, transferred file size is rounded up to be a multiple of 4096 bytes.
Files that are not aligned and bigger than 8M trigger the issue.

I assume we had not noticed this before because we either flash disk images
which are 4K aligned or we flash small images which were < 8M.

I haven't looked into the fastboot client code, but a look would be worthwhile
to decide how to proceed.

>>>> It saves upload time anyway, at least for the initramfs, so it's a good idea to use sparse images, anyway.
>>>
>>> Sparse is a compression algorithm, albeit a very primitive one. Your kernel and
>>> initrd should already be compressed, so if you have savings from compressing
>>> them again with sparse, there's something wrong IMO.
>>>
>>> The device tree is small enough that it shouldn't matter.
> 
> As mentioned, I don't think double compression is useful.
> On our side, we can likely just use -S 1 to restore the old behavior.


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