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

On Wed, Nov 28, 2007 at 10:41:17AM -0800, Chuck McIntyre wrote:
> On Nov 28, 2007 5:24 AM, Rafał Kupka <rkupka+Listy.Xen@xxxxxxxxxxxxx> wrote:

> > Could you send e820 memory map as seen by Xen?
> > $ xm dmesg
> > lines after "Xen-e820 RAM map:"
> >
> Here is the output form the 4GB system
> (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].

> > Did grub command displaymem shows all memory?
> No, grub displaymem shows:
> grub> displaymem
>  EISA Memory BIOS Interface is present
>  Address Map BIOS Interface is present
>  Lower memory: 631K, Upper memory (to first chipset hole): 3619776K

Yes, it's this strange bug in grub I spot some time ago.
Please look at Debian bug #419994:

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

> This is again from the 4GB system. Do you need me to provide the same
> details for the 8GB system? I can but it's more difficult as it is
> nominally in use as a test system for someone right now (albeit not
> running as many images as we would like).

It's probably very same problem here.

[1] But linux and grub both use int 15h...
[2] Make sure that files in /boot/grub directory are new, some systems
(Debian) don't update it during grub package update.
Great software without the knowledge to run it is pretty useless.
(Linux Gazette #1)

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