Re: [Qemu-devel] [PATCH 0/5] pc: make ROMs resizeable

[Michael S. Tsirkin]

On Tue, Nov 18, 2014 at 03:47:16PM +0100, Markus Armbruster wrote:
> "Michael S. Tsirkin" <address@hidden> writes:
> 
> > At the moment we migrate ROMs which reside in fw cfg, which allows
> > changing ROM code at will, and supports migrating largish blocks early,
> > with good performance.
> > However, we are running into a problem: changing size breaks
> > migration every time.
> 
> Pardon my ignorance... changing ROM in migration?  I would expect
> migration to be as transparent for ROM as it is for RAM.  What am I
> missing?
> 
> [...]

Nothing really.

We migrate RAM size too - but if there's a mismatch, migration fails.

RAM size is user configurable.

ROM is used internally so we have to figure out the size,
and it turned out to be a hard problem, so we end up maintaining
logic for ROM size "like we did in 1.7" "like we did in 2.0" etc.

I don't want to add any more: let's just accept whatever is migrated,
and stick to it.



-- 
MST