From: Andrew Lunn <andrew@lunn.ch>
To: Mike Sweeney <msweeney77@gmail.com>
Cc: ecos-discuss@sourceware.org
Subject: Re: [ECOS] ARM HAL CYGHWR_HAL_ROM_VADDR question
Date: Sun, 03 Jun 2007 15:22:00 -0000 [thread overview]
Message-ID: <20070603152234.GB22660@lunn.ch> (raw)
In-Reply-To: <70d4f620706030810i71f73f55j43723b9c617037df@mail.gmail.com>
On Sun, Jun 03, 2007 at 11:10:07AM -0400, Mike Sweeney wrote:
> Can someone please explain to me what CYGHWR_HAL_ROM_VADDR is used for
> in the ARM HAL? I see the comment about it in vectors.S but it makes
> no sense to me. It further confuses me because it affects the
> UNMAPPED_PTR macro which is only used when setting up the reset vector
> and not the other exception vectors. Can someone shed some light on
> what problem this solves?
Think about how the system works when at boot time the ROM is at
0x0. Then early in the boot sequence the ROM is remapped to a high
address and RAM is mapped to 0x0. Applications which run in ROM have
to be linked with the high address, but the first part of the boot
code, in particular the reset vector, needs to be linked for 0x0. If i
remember correctl, CYGHWR_HAL_ROM_VADDR is involved in this.
Andrew
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
next prev parent reply other threads:[~2007-06-03 15:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-03 15:10 Mike Sweeney
2007-06-03 15:22 ` Andrew Lunn [this message]
2007-06-03 23:51 ` Mike Sweeney
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=20070603152234.GB22660@lunn.ch \
--to=andrew@lunn.ch \
--cc=ecos-discuss@sourceware.org \
--cc=msweeney77@gmail.com \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).