Re: [Qemu-devel] [RFC PATCH 1/1] linux-user: Probe the guest base for shared objects when needed

[Alexander Graf]

On 28.06.2012, at 02:06, Paul Brook wrote:

>>> openSUSE uses a version patched so that IIUC 3G are reserved.
>>> Just today this failed on a system where swap got disabled and the
>>> mmap() thus failed.
>> 
>> Err... why?  We map with MAP_NORESERVE, so swap shouldn't matter...
> 
> I can't say if it's the same cause, but we fail with "ulimit -v 4046848".
> 
> Incidentally, it seems a strange that we only reserve 0xf7000000 bytes, not 
> the full 4G.

Uh, I think that was because of the vdso shared page that is allocated on top 
of -R.

Either way, this whole approach only works for 32-on-64. For 64-on-64, we can't 
reserve enough virtual memory on the host to satisfy the guest process for all 
archs.


Alex