Re: [PATCH 0/2] xen/arm: Couple of bug fixes when decompressing kernels

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.04.2021 17:21, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> Hi all,
> 
> The main goal of this series is to address the bug report [1]. It is not
> possible

...?

> While testing the series, I also noticed that it is not possible to
> re-use the same compressed kernel for multiple domains as the module
> will be overwritten during the first decompression.
> 
> I am still a bit undecided how to fix it. We can either create a new
> module for the uncompressed kernel and link with the compressed kernel.
> Or we could decompress everytime.
> 
> One inconvenience to kernel to only decompress once is we have to keep
> it until all the domains have booted. This may means a lot of memory to be
> wasted just for keeping the uncompressed kernel (one my setup, it takes
> ~3 times more space).
> 
> Any opinions on how to approach it?

Well, it's not "until all the domains have booted", but until all the
domains have had their kernel image placed in the designated piece of
memory. So while for the time being multiple decompression may indeed
be a reasonable approach, longer term one could populate all the
domains' memory in two steps - first just the kernel space for all of
them, then load the kernel(s), then populate the rest of the memory.

Jan