[SeaBIOS] [Qemu-devel] Minimum RAM size for PC machines?

[Kevin O'Connor]

On Wed, Mar 22, 2017 at 01:25:49PM +0100, Igor Mammedov wrote:
> On Wed, 22 Mar 2017 11:03:44 +0100
> Thomas Huth <thuth at redhat.com> wrote:
> > On 22.03.2017 10:08, Markus Armbruster wrote:
> > > Are we now ready to accept a simple & stupid patch that actually helps
> > > users, say letting boards that care declare minimum and maximum RAM
> > > size?  And make PC reject RAM size less than 1MiB, even though "someone"
> > > might conceivably have firmware that works with less?  
> > 
> > I'd say enforce a minimum RAM size on the normal "pc" and "q35" machine,
> > but still allow smaller sizes on the "isapc" machine. So if "someone"
> > comes around and claims to have a legacy firmware that wants less memory
> > than 1MiB, just point them to the isapc machine.
> > Just my 0.02 €.
> 
> We can print warning that minimum size will be enforced in 1-2
> releases since 2.9/10 and when it's enforced send users that need
> less to an old qemu version.

I did not think that QEMU ever worked on an x86 machine with less than
1MiB of ram.  Certainly SeaBIOS has never supported it.  I'm pretty
sure that Bochs BIOS (qemu < v0.12) did not support it either - its
ram detection system assumed a minimum of 1MiB.

My $.02 - I agree with Markus - place a minimum limit of 1MiB on x86
machines.  If someone is writing a new firmware, updating QEMU to
change the limit is the very least of their concerns.

-Kevin