Re: [Xen-users] xen dom0 32 bits memory is limited to 16GB?

["Marco Strullato" <marco.strullato@xxxxxxxxx>]

Hi all,

I've just downloaded the last grub from cvs, built and set up with the
option that allows me to specify the "mem" parameter. So I set this
parameter to 25G or 25600.
After boot I confirm that nothing has changed The system "see" only 16GB of ram.

So I excluded the boot loader, the kernel  that is "pae" with high
memory support. So the other part is xen. I believe there's a limit
somewhere so that a 32 bit dom0 can handle a maximun of 16GB.... but
where? I want to avoid this limit!

Thanks

Marco

2008/4/29 Rudi Ahlers <Rudi@xxxxxxxxxxx>:
>
> Marco Strullato wrote:
>
> > I don't think so: the linux kernel supports pae and pae can map up to
> > 64 GB of ram: read here
> > http://en.wikipedia.org/wiki/Physical_Address_Extension
> > Moreover, if you build the linux kernel you'll find the same: into
> > processor types and features the high memory supports can map to 64
> > GB.
> >
> >
> >
> > Marco
> >
> > 2008/4/29 Rudi Ahlers <Rudi@xxxxxxxxxxx>:
> >
> >
> > > Marco Strullato wrote:
> > >
> > >
> > >
> > > >
> > > > Hi all,
> > > > I'm reading that xen dom0 32 bits is limited to 16GB of ram (see
> > > > http://www.centos.org/modules/newbb/viewtopic.php?topic_id=12690)
> > > >
> > > > Is it true? How can I remove this limit?
> > > >
> > > > Thanks
> > > >
> > > > Marco
> > > >
> > > > _______________________________________________
> > > > Xen-users mailing list
> > > > Xen-users@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.xensource.com/xen-users
> > > >
> > > >
> > > >
> > > >
> > > >
> > >  That's a 32bit limit, not an OS limit. The only way around this is to
> use
> > > 64bit a OS :)
> > >
> > >  --
> > >
> > >  Kind Regards
> > >  Rudi Ahlers
> > >  CEO, SoftDux
> > >
> > >  Web:   http://www.SoftDux.com
> > >  Check out my technical blog, http://blog.softdux.com for Linux or other
> > > technical stuff, or visit http://www.WebHostingTalk.co.za for Web
> Hosting
> > > stuff
> > >
> > >
> > >
> > >
> >
>  Ok, so I answered before I checked the facts :)
>
>  This could be related to grub, as per this page:
> https://bugzilla.redhat.com/show_bug.cgi?id=250299#c5
>
>
>  I know I had the same problem when upgrading from 2GB to 4GB RAM. SO, I
> just installed the updated grub rpm, and reinstalled it on the HDD as such:
>
>  [root@venus ~]# history | grep grub
>   489  vi /etc/grub.conf
>   789  vi /boot/grub/menu.lst
>   881  history  | grep grub
>   903  grub-install /dev/sda
>   905  more /boot/grub/menu.lst
>   912  rpm -Uvh grub-0.97-14.x86_64.rpm
>   913  rpm -e grub-0.97-14.x86_64
>   914  rpm -Uvh grub-0.97-14.x86_64.rpm
>   915  grub-install /dev/sda
>
>
>  The last 2 (or 4) options are what you're looking for. It updates the grub
> RPM, and then reinstalls grub on the boot partition of /dev/sda
>
>
>
>
>  --
>
>
>  Kind Regards
>  Rudi Ahlers
>  CEO, SoftDux
>
>  Web:   http://www.SoftDux.com
>  Check out my technical blog, http://blog.softdux.com for Linux or other
> technical stuff, or visit http://www.WebHostingTalk.co.za for Web Hosting
> stuff
>
>

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