Re: adding support for above 2giga to kvm (include patchs)

[Ryan Harper <ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

* Izik Eidus <izike-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-08-14 10:49]:
> On Tue, 2007-08-14 at 10:09 -0500, Ryan Harper wrote:
> > * Izik Eidus <izik.eidus-atKUWr5tajBWk0Htik3J/w@public.gmane.org> [2007-08-14 01:29]:
> > > Hey Ryan,
> > > thanks for the testing, i hope you didnt have too much problems to get it working.
> > 
> > Sure, it wasn't too much trouble.  
> > 
> > > anyway as far as i can tell it wont have problem to drive up to 256 + 3.75 giga ram for guest.
> > > if we want it to drive systems with even more ram we have two options ( both very easily applied ):
> > > we can add another cmos byte to a "future reserved" byte, or we can use the 3 cmos bytes that i already added and say that
> > > we store memory in the above bios memory at multiplier of 1 MB.  
> > > it is important we decide now how we want to store the memory, that in the future when 256 + 3.75 giga of ram wont be enough
> > > we wouldn't have to change bochs bios again.
> > 
> > Yeah, I think we want to settle on a single method which gets us the
> > most memory as possible.  I think rather than doing the "future reserve"
> > we should go head an move over to 1MB multiplier.
> > 
> well this sound like a smart idea,
> but what we have to think about is:
> first in this way we have just 64 gigabyte of ram (unless we work with
> the extra cmos memory bytes)
> plus if we change the way we use the "normal cmos bytes", we arent
> breaking compatibility with really old stuff that check the cmos
> directly without doing bios interrupt? (i mean by ports)

Hrm, yes.  This might be an issue already.  I just booted memtest-86
v3.3 with 6G, and memtest says we have 528G of RAM.  Hrm, even below 2G,
memtest still reports bogus memory values.

We might need to go look at a newer BIOS spec to see how this is done in
newer bioses.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org

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