Re: [Qemu-devel] [PATCH 2/9] alpha-linux-user: Work around hosted mmap allocation problems

[Alexander Graf]

On 12.06.2012, at 16:57, Richard Henderson <address@hidden> wrote:

> On 2012-06-12 07:53, Alexander Graf wrote:
>> 
>> 
>> On 12.06.2012, at 16:27, Richard Henderson <address@hidden> wrote:
>> 
>>> On 2012-06-12 07:12, Andreas Färber wrote:
>>>> This looks fishy to me... why should the kernel use a bigger address
>>>> space than hardware? For arm on x86_64 such a workaround was not
>>>> necessary iirc.
>>> 
>>> I can tell you what I observe.  That with a certain sequence of
>>> allocations the x86_64 kernel will quit accepting an address "near"
>>> (1<<38) as a hint for where to allocate memory and begin returning
>>> an addresses near (1<<48).  
>> 
>> Hrm, does -R work for you? :)
> 
> Lol.
> 
> Actually I've tried it a couple of times: -R 32G.  

32G is way too much. Do you have to preallocate such a big address space? 
Usually 1G should be good enough for most programs, no?

Alex

> And, no, it 
> doesn't work very well.  ;-)
> 
> 
> r~