Re: [Qemu-devel] incorrect memory size inside vm

[Andrey Korolyov]

On Thu, Jun 18, 2015 at 1:44 AM, Vasiliy Tolstov <address@hidden> wrote:
> 2015-06-18 1:40 GMT+03:00 Andrey Korolyov <address@hidden>:
>>
>> Yes, but I`m afraid that I don`t fully understand why do you need this
>> when pure hotplug mechanism is available, aside may be nice memory
>> stats from balloon and easy-to-use deflation. Just populate a couple
>> of static dimms with small enough 'base' e820 memory and use  balloon
>> on this setup, you`ll get the reserved memory footprint as small as it
>> would be in setup with equal overall amount of memory populated via
>> BIOS. For example, you may use -m 128 ... {handful amount of memory
>> placed in memory slots} setup to achieve the thing you want.
>
>
> I have debian wheezy guests with 3.4 kernels (or 3.2..) and many
> others like 32 centos 6, opensue , ubuntu, and other.
> Does memory hotplug works with this distros (kernels)?
>

Whoosh... technically it is possible but it would be an incompatible
fork for the upstreams for both SeaBIOS and Qemu, because the generic
way of plugging DIMMs in is available down to at least generic 2.6.32.
Except may be Centos where broken kabi would bring great consequences,
it may be better to just provide a backport repository with newer
kernels, but it doesn`t sound very optimistic. For the history
records, the initial hotplug support proposal provided by Vasilis
Liaskovitis a couple of years ago worked in an exact way you are
suggesting to, but its resurrection would mean emulator and rom code
alteration, as I said above.