linux-kernel - Re: Help using initramfs

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Date:	Wed, 26 Nov 2008 10:51:22 +0000
From:	Mark Jackson <mpfj@...c.co.uk>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	linux-kernel@...r.kernel.org, mrustad@...il.com
Subject: Re: Help using initramfs

H. Peter Anvin wrote:
> Mark Jackson wrote:
>> I'm not sure if this is the correct place to be asking, but I've spend a
>> while searching Google and am still no wiser.
>>
>> I'm looking to use initramfs to create a simple bootable linux distro
>> for our AVR32 based boards.
>>
>> However, I have hit a brick wall at nearly the first step.
>>
>> So far I've managed to create a "bloated" kernel containing the
>> initramfs directory structure and I'm just trying to get a simple "Hello
>> World" test app running.
>>
>> The kernel boots, and the app runs, but I get no output on the console.
>>
> 
> Make sure /dev/null, /dev/zero, and *especially* /dev/console exists in
> your initramfs.

Aha ... after much head scratching, I now understand my error.

As you suggested, I hadn't correctly made my /dev entries.

Thanks.

My next problem is this ... below is a copy of my /init script ...

#!/bin/sh
#Mount things needed by this script
mount -t proc proc /proc
mount -t sysfs sysfs /sys
mdev -s
echo "wibble"
echo "qwerty" > /dev/console
exec /sbin/init
exit 0

And this is the console output ...

mount: permission denied. (are you root?)
mount: permission denied. (are you root?)
mdev: /sys/block: No such file or directory
mdev: /sys/class: No such file or directory
wibble
qwerty
Mounting virtual filesystems:
mount: permission denied. (are you root?)
   mount /proc failed
mount: permission denied. (are you root?)
   mount /sys failed
mount: permission denied. (are you root?)
   mount /dev failed
mount: permission denied. (are you root?)
   mount /config failed
mount: permission denied. (are you root?)
   mount /tmp failed
mount: permission denied. (are you root?)
   mount /var/run failed
mount: permission denied. (are you root?)
   mount /var/log failed
   WARNING: not able to mount all virtual file systems
Setting up mdev: eth0: link up (100/Full)
/etc/init.d/S01hotplug: line 11: can't create /proc/sys/kernel/hotplug: 
nonexistent directory
failed
Setting hostname: hostname: permission denied. (are you root?)
failed
Starting syslogd: done
Log messages to syslog: /etc/init.d/S08syslog: line 24: can't create 
/proc/sys/kernel/printk: nonexistent directory
failed
Starting klogd: done
Probing modules:
Mounting local filesystems: mount: mounting /dev/mmcblk0 on 
/media/sdcard failed: No such file or directory
failed
Network interfaces: ifconfig: SIOCSIFADDR: Permission denied
ifconfig: SIOCSIFFLAGS: Permission denied
failed
/etc/init.d/S50lighttpd: line 4: /usr/sbin/lighttpd: not found
can't open /dev/ttyS1: No such file or director
can't open /dev/ttyS1: No such file or director
can't open /dev/ttyS1: No such file or director

Does /init not inherently run as root ?

If not, how do I fix the problem ?

Mark
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