Re: [PATCH] shmem: add shmem_size option, set filesystem size

[-Gary- <me@garybgenett.net>]

> > A specific case where this is necessary would be if the initramfs were
> > larger than half of the memory, such as a 2.5GB filesystem with 4GB of
> > memory.  Without this option, this causes a kernel panic.  With this
> > option, the user may specify something like 75%, which would allow the
> > filesystem into memory, while still leaving enough resources to run
> > a functioning system.
> 
> Why would anyone need such a large an initramfs?

Thank you for such a quick response, Qian!  I really appreciate your question and consideration of my submission.

The use case here is a live distribution, where the initramfs is a standard filesystem.  It is common for these types of distributions to unpack root into memory.  Most of them use SquashFS, and resize shmem using a smaller initramfs first.

https://grml.org

In my case, I am unpacking straight from the initramfs to alleviate the need for a separate file and packaging everything in an ISO.  It very well could be that I am the only person who has ever needed this, but it has been a requirement for my distribution.

https://sourceforge.net/projects/gary-os
https://github.com/garybgenett/gary-os

It is also possible that other live distributions are taking the approach they are because of the current inability to load an initrd/initramfs directly into memory without manually resizing the shmem filesystem first.

Since I was in there hacking the feature, anyway, I thought it would be worth submitting.

At the least, it should be a "#define", or something.  Right now it is a hard-coded magic token.

Thoughts?

-- Gary