Re: qemu 6.1.0 - i386 <= 2GB?

[Narcis Garcia]

El 29/11/21 a les 9:33, Frans de Boer ha escrit:
> On 29/11/2021 08:46, Narcis Garcia wrote:
> > El 28/11/21 a les 19:42, Frans de Boer ha escrit:
> > > On 24/11/2021 09:42, Narcis Garcia wrote:
> > > > El 23/11/21 a les 14:33, Frans de Boer ha escrit:
> > > > > On 23/11/2021 11:44, Narcis Garcia wrote:
> > > > > > El 23/11/21 a les 10:03, Frans de Boer ha escrit:
> > > > > > > On 23/11/2021 09:27, Narcis Garcia wrote:
> > > > > > > > Some 32-bit system can't handle more than 512 MiB of RAM, and 
> > > > > > > > some 32-bit systems can handle up to 64 GiB.
> > > > > > > >
> > > > > > > > This is not related to memory assigned by Qemu to VE.
> > > > > > > >
> > > > > > > >
> > > > > > > > Narcis Garcia
> > > > > > > >
> > > > > > > > El 22/11/21 a les 18:38, Frans de Boer ha escrit:
> > > > > > > > > LS,
> > > > > > > > >
> > > > > > > > > OK, 32-bit systems can't handle more than 4GB memory. So, I 
> > > > > > > > > specify '-m 4096' and still get only 2GB. Is this (very) old 
> > > > > > > > > bug still not resolved or is it a feature now?
> > > > > > > > >
> > > > > > > > > Regards, Frans.
> > > > > > > In theory an 32-bit processor can handle up-to 4GB of physical 
> > > > > > > memory. However, due to limitations of some chip sets, the 
> > > > > > > maximum amount of memory was often 512 MB or 1 GB. At that time 
> > > > > > > the chip sets where lagging behind the processor capabilities.
> > > > > > > With newer chip sets it became practically possible to address 4 
> > > > > > > GB and when using PAE, even beyond that. Although in case of the 
> > > > > > > latter, the address space for a single process was always limited 
> > > > > > > to 4 GB.
> > > > > > >
> > > > > > > So, whatever way you see it, the 2 GB limit imposed by QEMU seems 
> > > > > > > rather arbitrary.
> > > > > > >
> > > > > > > --- Frans.
> > > > > >
> > > > > > Before talking about 64 GiB limit, I just tried 
> > > > > > ubuntu-mate-18.04.1-desktop-i386 in a Qemu 5.2.0 VM
> > > > > > 50 GiB assigned and guest OS detects and uses it.
> > > > > Then, what type of CPU did you specify?
> > > >
> > > > I've tried now with these four modes:
> > > > qemu-system-x86_64 -m 51200 -cpu host [intel core i5]
> > > > qemu-system-x86_64 -m 51200 -cpu pentium2
> > > > qemu-system-i386 -m 51200 -cpu host
> > > > qemu-system-i386 -m 51200 -cpu pentium2
> > > > qemu-system-i386 -m 51200 -cpu kvm32
> > > >
> > > > each of them detect & use 50GiB of RAM.
> > > > Other parameters of interest:
> > > > -vga qxl -display gtk -enable-kvm -boot d -drive 
> > > > file=ubuntu-mate-18.04.1-desktop-i386.iso,media=cdrom,index=0
> > > >
> > > > * If I try with booting 64-bit OS (ubuntu-18.04-desktop-amd64) then 
> > > > I get Linux message "This kernel requires an x86-64 CPU, but only 
> > > > detected an i686 CPU." and it does not boot.
> > > > * If I try with "-cpu pentium" then I get Linux message "This kernel 
> > > > requires the following features not present on the CPU: pae cmov" 
> > > > and it does not boot.
> > > >
> > > > ARE YOU SURE you're using a modern operating system?
> > > Okay, I needed some time before I could continue.
> > >
> > > I am building my own version of a linux system, but use OpenSuse TW 
> > > (64-bit) as base. Updated almost every second day.
> > > Now, when I either use ´-cpu pentium´ or ´-cpu kvm32´, I never can 
> > > allocate more than 2 GB, no matter the -m size.
> > > I do see that virtual memory is being increased, but the available 
> > > memory for allocation is never more than 2GB.
> > >
> > > So, yes the requested memory is allocated - albeit virtual -, but the 
> > > excess above 2GB is never used.
> > >
> > > --- Frans.
> >
> > Are you sure you're using Linux [64-bit] kernel?
> > If not (32-bit), sure you're using PAE enabled Linux kernel.
> Yes, I am sure that my system is using a 64-bit version of Tumbleweed.
> Of course, the client in the VM is 32-bit.
> A 64-bit client (windows/linux) has no problem.
>
> I will download another 32-bit iso and check if that makes a difference.
>
> --- Frans.

Please, copy here the complete syntax of your VM launch, and try with a 
guest like the one I've tried with PAE support (ubuntu 18.04 i386)