Re: [PATCH v2] ubi: gluebi: Fix NULL pointer dereference caused by ftl notifier

Richard Weinberger
2024-06-17T18:32:44Z

----- Ursprüngliche Mail -----
> Von: "Gagan Sidhu" <broly@mac.com>
>> AFAICT, this log line is not part of the mainline kernel.
>
> this is mainline. it’s just not 6.x. it’s 4.14.

I've double checked and disagree.
This line comes from:
https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/generic/pending-4.14/480-mtd-set-rootfs-to-be-root-dev.patch;h=6cddaf01b75cb58cfb377f568f2c375af87e2f1b;hb=c3bd1321de1e0d814f5cfc4f494f6b2fb1f5133b

In recent OpenWRT kernels I see:
https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/generic/pending-5.15/493-ubi-set-ROOT_DEV-to-ubiblock-rootfs-if-unset.patch;h=266a6331c2acc0f7c17d9ac72f54659d31b56249;hb=HEAD

Looks like in recent versions the patch in question does *not* cause a regression.

>> (31, 12) would be mtdblock12.
>> How does your kernel know that mtdblock12 shall be the rootfs?
>
> this is an openwrt approach: https://openwrt.org/docs/techref/filesystems (under
> “technical details”, third paragraph)
>
> essentially there’s a feature they add to the kernel (via patch) where you can
> enable a feature that sets the root device based on the name of the partition.

So, this is all not mainline. :-/

> in this case as long as the volume within your ubi file contains the name
> “rootfs”, openwrt will follow it as it gets unpacked and set that as the
> rootdevice for you.

Thanks,
//richard