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

Jo-Philipp Wich jo at mein.io
Mon Apr 1 05:18:55 EDT 2019


> Felix had a good point about sysupgrade, where we would needlesly write few
> dozen MBs of 0s. In order to avoid that, I would simply add following qemu
> variants to x86:

I wonder what kind of storage media on x86 is so brittle that writing a
few dozen MB of 0s will cause any noticeable effect.

>  openwrt-x86-{64,generic,geode,legacy}-qemu-{rootfs,combined}-squashfs.img

Not opposed to that, but that nullifies the entire "save space on
servers" argument. Instead of having one set of images a few MB larger,
we have a completely new set of larger images *and* the existing ones.

> I'm wondering if we should introduce CONFIG_QEMU_SQUASHFS_PARTSIZE=32 and use
> this information for generating of images for QEMU.
> Without this config option I don't see, how could we handle this on x86. On
> armvirt/malta we could probably just set already available option
> CONFIG_TARGET_ROOTFS_PARTSIZE=32 and use that to pad the images.
> Or should we just forget about this QEMU specific CONFIG_QEMU_SQUASHFS_PARTSIZE
> and use CONFIG_TARGET_ROOTFS_PARTSIZE for QEMU images as well? We can decrease
> the default 256M to 32M on armvirt/malta.

I'd prefer the later option.

~ Jo

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