Re: pgd clarification

["Joseph A. Knapka" <jknapka@earthlink.net>]

Santosh Eraniose wrote:
> 
> Hello,
> In the mm_struct structure I notice only an entry for pgd_t* pgd.
> Cannot a process memory space occupy more that 4MB of virtual addr space.
> In that case how is one pgd sufficient?
> 1pgd can address 1024*4*1024 =4MB. or a 4k page

No. mm_struct->pgd is a pointer to a page directory, which maps the
entire 4G virtual address space. On x86, each of the 1024 elements
of the page directory addresses 4MB of virtual space, either
directly or via an additional layer of page tables.

HTH,

-- Joe

> I expected a list of pgd so that on a pagefault, the process would navigate
> thro the pgd, find the virtual address mapping to the physical page and
> then return the pte?
> Thanks in advance.
> regards
> 
> --
> Santosh Eraniose
> 
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