Re: [Xen-users] Xen 3 not seeing the right amount of RAM on x86_64

["Chuck McIntyre" <chuck.mcintyre@xxxxxxxxx>]

On Nov 29, 2007 2:09 AM, Rafał Kupka <rkupka+Listy.Xen@xxxxxxxxxxxxx> wrote:
> Hello,

Hi!

Thanks for your help, see my responses below.

> > (XEN) Physical RAM map:
> > (XEN)  0000000000000000 - 000000000009dc00 (usable)
> > (XEN)  0000000000100000 - 00000000dcff0000 (usable)
> > (XEN) System RAM: 3535MB (3620404kB)
> > (XEN) Xen heap: 14MB (14340kB)
> > (XEN) found SMP MP-table at 000ff780
> > (XEN) DMI present.
>
> Xen gets memory map from grub, unlike linux[1].

Do you have a reference for this? Is this intentional? My
understanding is that grub doesn't have any way to map around PCI BIOS
created RAM holes because it is such a low level (boot) piece of
software. Is this, then, a bug? Is there a way around it?

> Yes, it's this strange bug in grub I spot some time ago.
> Please look at Debian bug #419994:
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=419994

I'm not sure it's a grub bug though, since it works correctly in a
non-xen kernel.

Should I try a different boot loader?

> Can you try patch (with volatile unsigned long cont) and tell if it make
> any difference?[2]

Will try this, and see, just to be sure, in the meantime, if you could
provide reference for your assertion that Xen uses the boot loader to
get its RAM map, that would be very helpful.

Thanks again,
Chuck

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