Re: virtual address space ?

["karunakar rao" <karunakar.santhu@xxxxxxxxx>]

On Fri, Sep 19, 2008 at 5:54 PM, <patrick@xxxxxxxxxx> wrote:

On Fri, Sep 19, 2008 at 05:29:20PM +0530, nidhi mittal wrote:
> as if linear address is of 32 bits then total linear address space of 4GB is
> mapped to physical address space.
> then i wanted to ask
> Is this address space is split among all processes ?
> OR
> each process gets its independent full 4GB linear address space. ?

Each process gehts its independent 4GB linear address space.
The mapping work is done by the MMU.

HTH
--
Patrick Kirsch
http://spielux.de | Open Source Spiele, Bewertungen, Auftragsentwicklung


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The linear address space of a process is divided into two parts

    Linear addresses from 0x00000000 to 0xbfffffff can be addressed when the process runs in either User or Kernel Mode.

    Linear addresses from 0xc0000000 to0xffffffff can be addressed only when the process runs in Kernel Mode.

When a process runs in User Mode, it issues linear addresses smaller than 0xc0000000 when it runs in Kernel Mode, it is executing kernel code and the linear addresses issued are greater than or equal to 0xc0000000. In some cases, however, the kernel must access the User Mode linear address space to retrieve or store data.

 

-karunakar