From: "Mike Sweeney" <msweeney77@gmail.com>
To: "Mike Sweeney" <msweeney77@gmail.com>, ecos-discuss@sourceware.org
Subject: Re: [ECOS] ARM HAL CYGHWR_HAL_ROM_VADDR question
Date: Sun, 03 Jun 2007 23:51:00 -0000 [thread overview]
Message-ID: <70d4f620706031651kca60cdcr97e861714e2949a9@mail.gmail.com> (raw)
In-Reply-To: <20070603152234.GB22660@lunn.ch>
On 6/3/07, Andrew Lunn <andrew@lunn.ch> wrote:
> 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
Thanks for the reply. I figured that's what it is there for, but I
don't understand based on how it is being used in the existing HAL
code how it actually works to fix that issue. I don't understand how
the UNMAPPED macro trickery works. An explantation of an existing
platform that uses this would be great.
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
prev parent reply other threads:[~2007-06-03 23:51 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
2007-06-03 23:51 ` Mike Sweeney [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=70d4f620706031651kca60cdcr97e861714e2949a9@mail.gmail.com \
--to=msweeney77@gmail.com \
--cc=ecos-discuss@sourceware.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 read-only IMAP folder(s) and NNTP newsgroup(s).