memory type e820

[Sourish Mazumder]

Hi John,

I tried the pmap_mapdev() as suggested by you. Works perfectly. Thanks for
the information.

What is required, If I want to add this nvram memory to VM pages?

On Thu, Oct 30, 2014 at 11:23 PM, John Baldwin <jhb at freebsd.org> wrote:

> On Thursday, October 30, 2014 12:39:27 pm Sourish Mazumder wrote:
> > Hi John,
> >
> > I want to make a block device out of this nvram memory. So, I will need
> to
> > perform memcpy() operation into this memory.
> > Do I need to add this memory into the vm system, if I need to do
> operations
> > like memcpy().
>
> Ah, so you just need to map it.  The most expedient thing you can do for
> this
> is:
>
>         void *p;
>
>         p = pmap_mapdev(physaddr, len);
>
> (This uses an uncached mapping).
>
> When you are finished (e.g during a detach routine if you need to unload
> the
> driver) you can do:
>
>         pmap_unmapdev((vm_offset_t)p, len);
>
> Note that for a PCI BAR you would do something different, but for a
> resource
> you discover via the SMAP and is x86 specific this is ok.
>
> --
> John Baldwin
>



-- 
Sourish Mazumder
9986309755