Re: CPU hot-plug and RAM hot-add in virtual machines

From: Miroslav Lachman <>
Date: Wed, 21 Jul 2021 12:07:33 UTC
On 21/07/2021 12:45, Andriy Gapon wrote:
> On 21/07/2021 11:53, Miroslav Lachman wrote:
>> On 09/07/2021 13:16, Andriy Gapon wrote:


>> Thank you for your reply. I know nothing about system internals. Is it 
>> too much work to implement it or just nobody from developers need it 
>> thus nobody write the code? Virtualization is more and more popular 
>> these days so I think it will be useful for many users.
> In my opinion, both would be big changes.
> At the moment we do not have any support for offlining / onlining CPUs 
> and that would involve a lot of careful changes like safely updating CPU 
> sets, various CPU masks, etc.
> Ditto for the memory.  Updating page arrays, free memory accounting 
> structures, possibly some memory maps, etc.
> Definitely not a weekend project.

Thank you again. It really seems too complicated.

Miroslav Lachman