[OpenWrt-Devel] [PATCH 2/5] build: image: Add pad-to and pad-rootfs-squashfs helpers

[Petr Štetiar]

Felix Fietkau <nbd at nbd.name> [2019-03-30 09:18:39]:

> >> On 2019-03-29 15:07, Petr Štetiar wrote:
> > 
> > Should we simply add CONFIG_QEMU_SQUASHFS_IMAGES (enabled by default) and
> > CONFIG_QEMU_SQUASHFS_PARTSIZE=32 and use this information for generating of
> > images for QEMU? On armvirt/malta it will simply produce working images based
> > on this settings, on x86 it will produce two additional images usable in QEMU
> > as well:
>
> I would like to avoid adding generating padded images by default. 

To just save some space? We're gzipping the images by default, which makes
image padded to 256M just 2.7M big. I find 256M overkill for testing, so
that's why I've suggested 32M by default for QEMU padded images.

> I just came up with this simple script, which takes an existing image and
> pads it to full size: http://nbd.name/pad-image.pl With this, shipping
> padded images should be unnecessary.

Ok, if that is preferred, it's fine with me. But we should probably add some
note somewhere, that in order to test this images in QEMU (x86, armvirt,
malta), the images should be padded with this script in order to provide
usable images.

BTW that script needs some tweaking, it's producing here 2TB images from this file

http://downloads.openwrt.org/snapshots/targets/x86/64/openwrt-x86-64-rootfs-squashfs.img.gz

> >  openwrt-x86-64-qemu-combined-squashfs.img
> >  openwrt-x86-64-qemu-rootfs-squashfs.img
>
> Another semi-related thing: do we really need those separate rootfs
> images? We could save some download server storage space by dropping
> them. If necessary, we could make another script like the one above to
> extract it from the combined image.

On x86, the only use case which comes to my mind is kernel testing, otherwise
combined image is good enough (if I ommit the missing padding for QEMU).

On armivrt/malta those images are probably necessary, as there is no combined
image on this targets. Again, without padding the images are unusable as well.

-- ynezz

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