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

Felix Fietkau nbd at nbd.name
Sun Mar 31 16:21:59 EDT 2019

On 2019-03-31 20:41, Petr Štetiar wrote:
> 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.
Not building padded images saves build time, because the system doesn't
have to waste so many cycles compressing empty data.

>> 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.
I agree.

> 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
That's just the rootfs image, you're supposed to run the script on a
combined image. What do you need that rootfs image for?

- Felix

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