linux-kernel - Re: BGRT Pointer in System RAM

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Date:	Mon, 15 Jul 2013 20:00:39 -0400
From:	Parag Warudkar <parag.lkml@...il.com>
To:	Josh Triplett <josh@...htriplett.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	LKML <linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org
Subject: Re: BGRT Pointer in System RAM

On Mon, Jul 15, 2013 at 7:56 PM, Parag Warudkar <parag.lkml@...il.com> wrote:
> On Mon, Jul 15, 2013 at 7:04 PM, Josh Triplett <josh@...htriplett.org> wrote:
>
>> We do need to handle the case of a valid pointer into memory that e820
>> calls system RAM, as well as the case of a valid pointer into memory
>> reserved for the BIOS or similar, but not the case of an invalid
>> pointer.
>
> Would that be as simple as
>
>                      page_is_ram(

Damn shortcuts -
                        virt_addr = phys_to_virt(image->base_address);
                        if(page_is_ram(virt_to_page(virt_addr))) {
                            //direct read from virt addr
                        }

Would that suffice for the System RAM case or some other MM trickery
is involved?

Thanks,
Parag
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