From: mpeg.blue@free.fr (Mason)
To: linux-arm-kernel@lists.infradead.org
Subject: ARM page tables
Date: Wed, 10 Dec 2014 10:41:24 +0100 [thread overview]
Message-ID: <54881544.8040302@free.fr> (raw)
In-Reply-To: <20141210001632.GL11285@n2100.arm.linux.org.uk>
Hello Russel,
Russell King wrote:
> Mason wrote:
>
>> What's the name of the address of the page table?
>
> swapper_pg_dir
Got it.
arch/arm/kernel/head.S
/*
* swapper_pg_dir is the virtual address of the initial page table.
*/
.equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
#define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET)
PAGE_OFFSET = 0xC0000000
TEXT_OFFSET = $(textofs-y) = 0x00008000
PG_DIR_SIZE = 0x4000
Thus, in my case, swapper_pg_dir = 0xC0004000
> As we can see above, you asked for 0x00200000 bytes to be mapped from
> 0xf0800000. So, 0xf0800000 to 0xf09fffff will be mapped. The address
> which you are accessing falls within this range.
>
> So, there's a valid mapping. Assuming nothing on the bus raises an
> external abort, accesses to this address will succeed.
I was looking so hard for the tree, that I completely missed the forest.
Thanks for clearing my confusion.
By the way, wrt to the thread "Creating 16 MB super-sections for MMIO".
I'm thinking of writing a quick-and-dirty patch to test the impact on
our SoC of using a super-section for the 0-16MB region. Would there be
any interest in mainlining that?
Regards.
prev parent reply other threads:[~2014-12-10 9:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-09 17:21 ARM page tables Mason
2014-12-09 17:27 ` Russell King - ARM Linux
2014-12-09 22:59 ` Mason
2014-12-10 0:16 ` Russell King - ARM Linux
2014-12-10 9:41 ` Mason [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=54881544.8040302@free.fr \
--to=mpeg.blue@free.fr \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).