It is an arbitrary question that popped in my mind. However, I came to know that the constraints I stated in the previous mail is only restricted to x86 only.Now besides my first questions , I have one more question, Why x86 only?
--
On Tue, May 14, 2013 at 2:34 AM, Sergio Andrés Gómez del Real <sergio.g.delreal@xxxxxxxxx> wrote:
Sure, I forgot what you said; precisely the mechanism allows to use
lots of linear space without necessarily allocating physical memory
(demand paging and the like).
What about the rest of what I said? Is it correct or is there
something wrong about it?
Thanks.
On 5/13/13, Valdis.Kletnieks@xxxxxx <Valdis.Kletnieks@xxxxxx> wrote:
> On Mon, 13 May 2013 14:11:22 -0500, Sergio Andr said:
>
>> 2. When user applications allocates memory, the kernel must allocate
>> virtual memory and physical memory, right?
>
> Wrong. If userspace allocates (say) 15M of memory, the kernel has every
> right
> to overcommit and not actually allocate either physical memory or backing
> page
> space for all 15M. It instead maps it as a non-existent virtual address,
> and
> if/when the application actually touches the page, it generates a page
> fault,
> and *then* the kernel does the allocating of physical memory and maybe swap
> space.
>
>
Regards,
Paul Davies C
vivafoss.blogspot.com
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