Re: KVM RAM limitation

[Daniel Bareiro <dbareiro@uol.com.ar>]

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Hi, Brian.

On Wednesday, 03 February 2010 16:44:28 -0600,
Brian Jackson wrote:

> > Anthony Liguori wrote:
> > >>> Are you sure you enabled KVM? Are you sure you are using the KVM
> > >>> binary and not some QEMU binary that's sitting around. This is one
> > >>> of those situations where the KVM command you are running might
> > >>> help.  Also the same binary you are running's version ($QEMU_BIN -h
> > >>> 
> > >>> | head -n1)

> > >> wilson:/usr/local/qemu-kvm/bin# ./qemu-system-x86_64 -h | head -n1
> > >> QEMU PC emulator version 0.12.2 (qemu-kvm-0.12.2), Copyright (c)
> > >> 2003-2008 Fabrice Bellard
> > >> 
> > >> 
> > >> The procedure that I used to compile qemu-kvm is the same of always:
> > >> to download qemu-kvm-0.12.2, to install the packages (Debian)
> > >> zlib1g-dev and libpci-dev, and to compile of the following way:
> > >> 
> > >> # cd qemu-kvm-0.12.2
> > >> # ./configure --prefix=/usr/local/qemu-kvm
> > >> # make
> > >> # make install
> > >> 
> > >> Until the moment I never got to use qemu-kvm with VMs of more than
> > >> 2048 MB. In an installation that I have with KVM-88 and kernel x86_64
> > >> I don't have this problem.

> > > QEMU and KVM only support 2GB of memory on a 32-bit host.
> > > 
> > > Both need to create a userspace mapping of the guests memory.  In a
> > > 32-bit environment, you only have enough usable address space in a
> > > process to create a 2GB region.
 
> > But, according to what I read in the link [1] that commented, just by to
> > have a x86_64 kernel would have to be sufficient to serve more than 2047
> > MB of RAM.

> The kvm userspace would also have to be compiled as a 64bit binary.
> Possibly statically compiled somewhere else (if that's even possible)
> or with a 64bit chroot.

Hmmm... and there is some way to compile qemu-kvm as a 64bit binary on a
operating system userspace of 32bit?

I tried with ARCH=x86_64 with make but when using this I obtain several
messages of the type "cast to/from pointer from/to integer of different
size".

Thanks for your reply.

Regards,
Daniel
-- 
Mi frase del día:
An algorithm must be seen to be believed.
		-- D. E. Knuth

Daniel Bareiro - GNU/Linux registered user #188.598
Proudly running Debian GNU/Linux with uptime:
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