[Qemu-devel] How to increase ram beyond 756 MB ?

[Qemu-devel] How to increase ram beyond 756 MB ?

[मनीष शर्मा]

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Hi All,

I am using arm on x86, running Linux 2.6.33 as guest and fedora 14 as host.
And using Realview board inside Qemu Machine.

Even though I passed 1024 MB as qemu memory in command line,
I can only see ~756MB given to guest. Also I tried passing more than
1024 MB say 2048 MB But I am unable to see increase in RAM in Guest OS.
I checked the /proc/meminfo for guest OS memory details.

What do I missed ? Any help is higly appreciated.

regards,
Manish

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-मनीष

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Re: [Qemu-devel] How to increase ram beyond 756 MB ?

[Peter Maydell]

2011/6/14 मनीष शर्मा <manishs.in@gmail.com>:
> I am using arm on x86, running Linux 2.6.33 as guest and fedora 14 as host.
> And using Realview board inside Qemu Machine.

Do you mean "realview-eb", "realview-eb-mpcore", "realview-pb-a9",
or "realview-pbx-a9" ? They are different models.

> Even though I passed 1024 MB as qemu memory in command line,
> I can only see ~756MB given to guest. Also I tried passing more than
> 1024 MB say 2048 MB But I am unable to see increase in RAM in Guest OS.
> I checked the /proc/meminfo for guest OS memory details.

For both "realview-eb" and "realview-eb-mpcore" the maximum memory
allowed is 256MB, because the hardware we are modelled has an
address space layout which does not permit more. If you're using
those models, then to use more RAM you must use a different model.

"realview-pb-a9" and "realview-pbx-a9" should both in theory
support 1024MB of RAM as a maximum. Typically to make this work
you need to both pass QEMU the "-m 1024" option (to model the
extra RAM) and also pass the guest kernel an option like "mem=1024M".
(However the pb-a9 hardware has 512MB of RAM as a maximum and
we are providing extra modelled RAM in a "reserved" section of
the address space, so it's possible the guest kernel wouldn't
try to use it.)

-- PMM

[Qemu-devel] Fwd: How to increase ram beyond 756 MB ?

[मनीष शर्मा]

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---------- Forwarded message ----------
From: मनीष शर्मा <manishs.in@gmail.com>
Date: 2011/6/14
Subject: Re: [Qemu-devel] How to increase ram beyond 756 MB ?
To: Peter Maydell <peter.maydell@linaro.org>


Thanks Peter.

I am able to change memory size in guest  to 1024 MB now.
After making small change in my kernel file realview_pbx.c.
To changed the address to 0x70000000 instead of 0x80000000
where qemu 0.14.0 is registering the memory.
realview_pbx_fixup () {
....
*-meminfo->bank[2].start = 0x80000000   *
+ meminfo->bank[2].start = 0x70000000
...
}

And to enable *High Memory support* in my kernel.
Now its showing 1024 MB.

Thanks a lot for such a quick reply.

regards,
Manish
2011/6/14 Peter Maydell <peter.maydell@linaro.org>

> 2011/6/14 मनीष शर्मा <manishs.in@gmail.com>:
> > I am using arm on x86, running Linux 2.6.33 as guest and fedora 14 as
> host.
> > And using Realview board inside Qemu Machine.
>
> Do you mean "realview-eb", "realview-eb-mpcore", "realview-pb-a9",
> or "realview-pbx-a9" ? They are different models.
>
> > Even though I passed 1024 MB as qemu memory in command line,
> > I can only see ~756MB given to guest. Also I tried passing more than
> > 1024 MB say 2048 MB But I am unable to see increase in RAM in Guest OS.
> > I checked the /proc/meminfo for guest OS memory details.
>
> For both "realview-eb" and "realview-eb-mpcore" the maximum memory
> allowed is 256MB, because the hardware we are modelled has an
> address space layout which does not permit more. If you're using
> those models, then to use more RAM you must use a different model.
>
> "realview-pb-a9" and "realview-pbx-a9" should both in theory
> support 1024MB of RAM as a maximum. Typically to make this work
> you need to both pass QEMU the "-m 1024" option (to model the
> extra RAM) and also pass the guest kernel an option like "mem=1024M".
> (However the pb-a9 hardware has 512MB of RAM as a maximum and
> we are providing extra modelled RAM in a "reserved" section of
> the address space, so it's possible the guest kernel wouldn't
> try to use it.)
>
> -- PMM
>



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-मनीष



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-मनीष

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