[U-Boot] stopping u-boot from booting an old image in RAM.
If I boot this unit, then remove the SD card it booted from and reset it, it happily boots some Linux image which is lying around in memory.
It even does it after a short power-off power-on sequence.
I think that's horrible behaviour.
I was told I could use && instead of ; between the commands in the bootcmd string to stop this, but that barfed, and then I was told that maybe && only existed if "scripting is enabled"
Could anyone please talk me through the steps of either
1. doing what it takes to enable this && feature, so that if it fails to find the card, it doesn't go on and try to boot.
or
2. something else that will do it, such as so effectively buggering up an image that has been booted from that it will never be re-used
:-)
TVM
David Collier
www.dexdyne.com
-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of David Collier Sent: 21 October 2009 16:08 To: u-boot@lists.denx.de Subject: [U-Boot] stopping u-boot from booting an old image in RAM.
If I boot this unit, then remove the SD card it booted from and reset it, it happily boots some Linux image which is lying around in memory.
It even does it after a short power-off power-on sequence.
I think that's horrible behaviour.
I was told I could use && instead of ; between the commands in the bootcmd string to stop this, but that barfed, and then I was told that maybe && only existed if "scripting is enabled"
Could anyone please talk me through the steps of either
- doing what it takes to enable this && feature, so that if it fails to
find the card, it doesn't go on and try to boot.
or
- something else that will do it, such as so effectively buggering up an
image that has been booted from that it will never be re-used
:-)
TVM
David Collier
Probably a simple mw (memory write) to the entry point of linux, before You attempt to reload the image, would do the trick?
Usage: mw [.b, .w, .l] address value [count]
Nick.
Dear "Thompson, Nick (GE EntSol, Intelligent Platforms)",
In message 610D18D1F0BB204D8AB39BB1C42187E8041E739E@LONMLVEM09.e2k.ad.ge.com you wrote:
- something else that will do it, such as so effectively buggering up an
image that has been booted from that it will never be re-used
...
Probably a simple mw (memory write) to the entry point of linux, before You attempt to reload the image, would do the trick?
This is not needed. Commands return return codes, and the command line parser provides ways to act on these. It's all written in the documentation.
Best regards,
Wolfgang Denk
In article 610D18D1F0BB204D8AB39BB1C42187E8041E739E@LONMLVEM09.e2k.ad.ge.com, Nick.Thompson@gefanuc.com (Thompson, Nick (GE EntSol, Intelligent Platforms)) wrote:
*From:* "Thompson, Nick (GE EntSol, Intelligent Platforms)" Nick.Thompson@gefanuc.com *To:* from_denx_uboot@dexdyne.com, u-boot@lists.denx.de *Date:* Wed, 21 Oct 2009 16:39:18 +0100
-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of David Collier Sent: 21 October 2009 16:08 To: u-boot@lists.denx.de Subject: [U-Boot] stopping u-boot from booting an old image in RAM.
If I boot this unit, then remove the SD card it booted from and reset it, it happily boots some Linux image which is lying around in memory.
It even does it after a short power-off power-on sequence.
I think that's horrible behaviour.
I was told I could use && instead of ; between the commands in the bootcmd string to stop this, but that barfed, and then I was told that maybe && only existed if "scripting is enabled"
Could anyone please talk me through the steps of either
- doing what it takes to enable this && feature, so that if it
fails to find the card, it doesn't go on and try to boot.
or
- something else that will do it, such as so effectively
buggering up an image that has been booted from that it will never be re-used
:-)
TVM
David Collier
Probably a simple mw (memory write) to the entry point of linux, before You attempt to reload the image, would do the trick?
Usage: mw [.b, .w, .l] address value [count]
Nick.
so something like
#define CONFIG_BOOTCOMMAND \ "mmcinit ; mw 0x10400000 55 ; ext2load mmc 0:1 0x10400000 /boot/uImage ; bootm 0x10400000"
????
That looks simple enough
David Collier
www.dexdyne.com
Dear "David Collier",
In message <memo.20091021160842.4412A@postmaster+dexdyne.com.cix.co.uk> you wrote:
If I boot this unit, then remove the SD card it booted from and reset it, it happily boots some Linux image which is lying around in memory.
Maybe you should start reading the documentation?
It even does it after a short power-off power-on sequence.
It takes time until memory loses it's content, and as long as the checksums are OK the image is still valid. It is up to you to provide a sane boot command which checks for error code.
I think that's horrible behaviour.
Indeed - but that's not U-Boot's fault, it's horrible programming by the user, i. e. yourself.
I was told I could use && instead of ; between the commands in the bootcmd string to stop this, but that barfed, and then I was told that
You really should read the documentation, at least the FAQ, for example "14.2.16. How the Command Line Parsing Works" at http://www.denx.de/wiki/view/DULG/CommandLineParsing
maybe && only existed if "scripting is enabled"
Whoever told you that used poor language. What he meant was: if the Hush shell is configured as command line parser for your board.
Could anyone please talk me through the steps of either
- doing what it takes to enable this && feature, so that if it fails to
find the card, it doesn't go on and try to boot.
To enable the hush shell, you have to set (at least) the CONFIG_SYS_HUSH_PARSER configuration option in your board config file. But even the old, simple command line parser can be used to do what you want. Just RTFM.
- something else that will do it, such as so effectively buggering up an
image that has been booted from that it will never be re-used
I cannot parse that. If an image has been booted, U-Boot is gone and out of the way, and whatever code was in the image is running.
Best regards,
Wolfgang Denk
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de "Just Say No." - Nancy Reagan "No." - Ronald Reagan
now that I have read TFM...
I find that the easier way to do this, rather than installing hush and using && would have been to
define setenv x mmcinit setenv y .... setenv z bootm
setenv bootcmd run x y z
in which case y would only run if x succeeded.
but I like hush and don't regret doing it
David
In article <memo.20091021160842.4412A@postmaster+dexdyne.com.cix.co.uk>, from_denx_uboot@dexdyne.com (David Collier) wrote:
*From:* "David Collier" from_denx_uboot@dexdyne.com *To:* u-boot@lists.denx.de *Date:* Wed, 21 Oct 2009 16:08 +0100 (BST)
If I boot this unit, then remove the SD card it booted from and reset it, it happily boots some Linux image which is lying around in memory.
It even does it after a short power-off power-on sequence.
I think that's horrible behaviour.
I was told I could use && instead of ; between the commands in the bootcmd string to stop this, but that barfed, and then I was told that maybe && only existed if "scripting is enabled"
Could anyone please talk me through the steps of either
- doing what it takes to enable this && feature, so that if it
fails to find the card, it doesn't go on and try to boot.
or
- something else that will do it, such as so effectively buggering
up an image that has been booted from that it will never be re-used
:-)
TVM
David Collier
www.dexdyne.com _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
David Collier
www.dexdyne.com
participants (3)
-
David Collier -
Thompson, Nick (GE EntSol, Intelligent Platforms) -
Wolfgang Denk