Re: [PATCH 1/2] init: ensure that /dev/console is (nearly) always available in initramfs

From: Rob Landley

Date: Mon Feb 23 2026 - 14:45:47 EST

On 2/23/26 11:34, Askar Safin wrote:

Rob Landley <rob@xxxxxxxxxxx>:

The real problem isn't cpio, it's that the kernel interface

So there is some bug here?

Then, please, describe properly this bug.

I. e. using usual formula "steps to reproduce - what I got - what I expected to see".

I think that the kernel special case creating files in initramfs is the wrong design approach, but it would address the problem and it's what the kernel already did in a different codepath.

Also, does the kernel broke *documented* feature? If indeed some
*documented* feature doesn't work, then this is indeed very real bug.

Documentation/filesystems/ramfs-rootfs-initramfs.txt section "populating initramfs" described using the text file format back in 2005 (https://github.com/mpe/linux-fullhistory/commit/7f46a240b0a1 line 135) and then commit https://github.com/mpe/linux-fullhistory/commit/99aef427e206f a year later described running usr/gen_init_cpio to create those files from a directory to give you an easy starting point to edit.

But I wrote that documentation, so it probably doesn't count.

I kindly ask you, please, please, describe this bug. I really want
to help you.

Back when the gen_init_cpio stuff let you create the file and consume the file separately so you could edit it in between, there was an easy way to address this problem by creating a cpio containing /dev/console as a regular user using the kernel plumbing. Then the kernel broke that and created a regression, which they decided to fix with special case code doing mknod within the kernel before launching PID 1, but only for one of two codepaths.

I think adding the special case hack to the other codepath is the wrong _WAY_ to fix it... but I guess that ship has sailed. I agree doing that can avoid the "init has no stdin/stdout/stderr" problem and thus address the issue.

(I still think if you have a CONFIG_DEVTMPFS_MOUNT config symbol, it should actually work, but that's a somewhat separate issue and a half-dozen patches ignored by linux-kernel for a decade now apparently argue otherwise...)

Rob