[Qemu-devel] Memory ballooning: wrong size?

[Qemu-devel] Memory ballooning: wrong size?

[Tiziano Müller]

Hi everyone

A look through recent changes didn't reveal anything (or I missed it),
so please excuse me if this is already fixed, but with qemu-1.1.1 and
guest linux kernels 3.3.x and 3.5.0 the size of the memory qemu sets
via memory ballooning and what the guest sees do not match:

hmp: `balloon 1024` -> `grep MemTotal /proc/meminfo`: 904565 kB

where I would rather expect 1019768 (which is what one would get with
'-m 1024' only).

The factor is constant 1/1024 with "-m 4096" but seems to change
depending on the (maximum) memory set via "-m ...".

I first expected libvirt to be the culprit here, but manually modifying
the balloon via monitor passthrough revealed that something between qemu
and guest virtio must go wrong.

Any ideas? What do/did I miss?

Thanks in advance,
Tiziano

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