Running the 32 bit x86 VM on a 64 bit Linux

Hello,

has anyone practical experience with running the 32-bit Linux x86 VM on
a x86-64 Linux?

Topics I'm interesed in:
- stability (compared to a "native" 32 bit environment)
- parallel installation of 32 bit and 64 bit libs vs. a 32 bit chroot
environment - any impact on stability?
- (not VM specific): is the amount of available physical memory limited
for each 32 bit OS process, or for all 32 bit processes combined (not
considering kernel space)? e.g. can I run 20 32-bit VMs, each allocating
1 GB of memory, on a machine with 64 GB RAM without a swapping spree?

Holger Kleinsorgen wrote:
> has anyone practical experience with running the 32-bit Linux x86 VM on
> a x86-64 Linux?

I've been running solely on 64bit Fedora for well over year now. I'm using 32-bit VM most of the time, and I run 64-bit VM occasionally for testing purposes.

> Topics I'm interesed in:
> - stability (compared to a "native" 32 bit environment)

I've never had any stability problems with the 32-bit VM, haven't noticed anything that would suggest that the 64-bit OS below is an issue. On the other hand I use my environment for development and testing only, I don't run any "production" servers on it. But I'd be surprised if the 64-bit OS caused troubles there.

> - parallel installation of 32 bit and 64 bit libs vs. a 32 bit chroot
> environment - any impact on stability?

I've never tried chrooted environment. IIRC, I had to patch up the OracleInterface to point to the right version of the client lib (/lib64 vs /lib) and I believe it worked fine. I have no problems using 32-bit libs with 32-bit VMs, I use StoreForOracle every day.

> - (not VM specific): is the amount of available physical memory limited
> for each 32 bit OS process, or for all 32 bit processes combined (not
> considering kernel space)? e.g. can I run 20 32-bit VMs, each allocating
> 1 GB of memory, on a machine with 64 GB RAM without a swapping spree?

I don't know anything about this stuff.

HTH,

Martin

We're running mixed vw32/vw64 images on a x86-64 Linux (Debian Etch AMD64 to be specific). We're not using a chroot'ed environment but have the ia32-libs package installed. AFAIK you can run multiple 1 GB totaling more than 4GB. If you're going to run only vw32 images and want to use x86-64 only for the extra memory you might look at a so-called 'bigmem' or 'hugemem' kernel. These use the Physical Address Extension to be able to address more than 4GB of memory.

hth,

Wouter

We regularly run production 32-bit images on 64-bit linux86 with no
problem.

Dave

Holger Kleinsorgen wrote:

Holger Kleinsorgen wrote:
> Hello,
>
> has anyone practical experience with running the 32-bit Linux x86 VM on
> a x86-64 Linux?

Yep, been doing it for over three years.

>
> Topics I'm interesed in:
> - stability (compared to a "native" 32 bit environment)

No problems. At all.

> - parallel installation of 32 bit and 64 bit libs vs. a 32 bit chroot
> environment - any impact on stability?

I generally only run in a 32-bit chroot environment to build 32-bit C
code, since running 32-bit apps in the 64-bit environment is so stable.

> - (not VM specific): is the amount of available physical memory limited
> for each 32 bit OS process, or for all 32 bit processes combined (not
> considering kernel space)? e.g. can I run 20 32-bit VMs, each allocating
> 1 GB of memory, on a machine with 64 GB RAM without a swapping spree?

I haven't tried this, but I believe that it should work.

-Martin