Re: Linux 2.6 : physical memory address and pid

[Allison <fireflyblue@gmail.com>]

Thanks for the answer! 

Another related question :

I need to gather all application pages by reading the page tables. 
The hard part is, I need to do this from a PCI device using DMA.  As I
understand it,  when a DMA is being performed, the pages are pinned in
memory . Since the PCI device has grabbed the bus, the processor is
not able to access memory to perform page replacement right ?
So, this is a form of mutual exclusion.

However, if I have to fetch the page struct, the process address space
of the process owning the page (I am ignoring shared pages to make
things simpler) and the page itself, will a scatter gather DMA make
sure that  the processor cannot modify any of these data structures
till the DMA is complete ? I am using Linux 2.6 and the i386
architecture.

thanks,
Allison





On Sat, 12 Mar 2005 17:23:23 -0800, Matt Mackall <mpm@selenic.com> wrote:
> On Sat, Mar 12, 2005 at 08:05:11PM -0500, firefly blue wrote:
> > Hi,
> >
> > With the 2.6 Linux kernel, I want to find, from the physical page
> > frame, the virtual address of the page loaded in the frame and the
> > process id of the process owning it.
> 
> Follow struct page->mapping to struct address_space. A page can be
> mapped into any number of processes and multiple times per process so
> you'll need to walk the data structures there.
> 
> --
> Mathematics is the supreme nostalgia of our time.
>