All of lore.kernel.org
 help / color / mirror / Atom feed
From: Andre Renaud <andre@bluewatersys.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] cpu/arm926ejs/start.S question
Date: Fri, 08 Jul 2011 09:38:52 +1200	[thread overview]
Message-ID: <4E16276C.3080303@bluewatersys.com> (raw)

Hello,
I am working on an i.MX25 board, and would like to know the recommended
mechanism for putting code in before the first instruction in the
executable, but outside the *_spl system.

Basically, the i.MX25 has a smart boot rom in the CPU, which will
extract the first block, and interpret it (as data, rather than
instructions). However, if I just use the linker script to put this
block before start.S, then U-Boot relocation gets messed up, as _start
is now not the beginning of the image, and a lot of the calculated
offsets are wrong.

At the moment I have this working with the following change in start.S:
--- cpu/arm926ejs/start.S       (revision 36)
+++ cpu/arm926ejs/start.S       (working copy)
@@ -53,6 +53,9 @@

 .globl _start
 _start:
+#ifdef CONFIG_PRE_START_INCLUDE
+#include CONFIG_PRE_START_INCLUDE
+#endif
        b       reset
 #ifdef CONFIG_PRELOADER
 /* No exception handlers in preloader */

and I then #define CONFIG_PRE_START_INCLUDE to be the assembler for the
i.MX25 specific boot code.

Is there a nicer way to go about this?

Regards,
Andre

             reply	other threads:[~2011-07-07 21:38 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-07 21:38 Andre Renaud [this message]
2011-07-07 22:34 ` [U-Boot] cpu/arm926ejs/start.S question Simon Glass
2011-07-07 22:40   ` Andre Renaud
2011-07-08  0:54 ` Fabio Estevam
2011-07-08  1:20   ` Andre Renaud
2011-07-08  1:38     ` Fabio Estevam
2011-07-08  1:42       ` Andre Renaud
2011-07-08  6:13     ` Stefano Babic
2011-07-11  4:59   ` Andre Renaud
2011-07-11 15:00     ` Fabio Estevam

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=4E16276C.3080303@bluewatersys.com \
    --to=andre@bluewatersys.com \
    --cc=u-boot@lists.denx.de \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.