Re: AW: AW: initrd rootfs ramdisk

Re: AW: AW: initrd rootfs ramdisk

[T Ziomek]

On Wed, 6 Jul 2005 d.grab@hima.com wrote:
>
> i solved my problem with u-boot and linux. Now i have my rootfs ramdisk
> mounted and functioning. But one output is weird.

Can I ask what what you had to change to get your initrd RAM disk working?
I'm having a very similar problem.

Thanks, Tom Ziomek

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AW: AW: AW: initrd rootfs ramdisk

[David Grab]

>> i solved my problem with u-boot and linux. Now i have my rootfs ramdisk
>> mounted and functioning. But one output is weird.

>Can I ask what what you had to change to get your initrd RAM disk working?
>I'm having a very similar problem.

Sure! :)

1. I used the ramdisk provided by ELDK from www.denx.de. A good description
is here
http://www.denx.de/twiki/bin/view/DULG/RootFileSystemDesignAndBuilding

2. Write ramdisk into flash at any address.

3. Configuring u-boot for command line parameters in
/u-boot/include/configs/<board.h>. These definitions i have made. BOOTARGS
are the command line parameters which u-boot passes to linux. BOOTCOMMAND is
not really necessary, but you only type bootd and not "bootm
<linux_flash_address> <ramdisk_flash_address>". So you don?t spend much time
for typing. ;) BOOTDELAY is disabled, because i actually don?t want an
autoboot of the linux kernel.

#define CONFIG_BOOTARGS		"console=ttyS1,115200 root=/dev/ram rw"
#define CONFIG_BOOTCOMMAND	"bootm ff000000 ff800000"    /* autoboot command
*/
#define CONFIG_BOOTDELAY	-1	 /* disable autoboot??     */

4. Now configuring linux kernel for ramdisk support. Following options are
needed.

CONFIG_CMDLINE_BOOL=y
CONFIG_CMDLINE=""

Enables command line parameters in linux kernel.

I also set following options to enable ramdisk support. Maybe there are some
more options which don?t concerns to ramdisk support.

#
# Block devices
#
# CONFIG_BLK_DEV_FD is not set
# CONFIG_BLK_CPQ_DA is not set
# CONFIG_BLK_CPQ_CISS_DA is not set
# CONFIG_BLK_DEV_DAC960 is not set
# CONFIG_BLK_DEV_UMEM is not set
# CONFIG_BLK_DEV_COW_COMMON is not set
CONFIG_BLK_DEV_LOOP=y
# CONFIG_BLK_DEV_CRYPTOLOOP is not set
# CONFIG_BLK_DEV_NBD is not set
# CONFIG_BLK_DEV_SX8 is not set
# CONFIG_BLK_DEV_UB is not set
CONFIG_BLK_DEV_RAM=y
CONFIG_BLK_DEV_RAM_COUNT=16
CONFIG_BLK_DEV_RAM_SIZE=4096
CONFIG_BLK_DEV_INITRD=y
CONFIG_INITRAMFS_SOURCE=""
# CONFIG_LBD is not set
# CONFIG_CDROM_PKTCDVD is not set

#
# File systems
#
CONFIG_EXT2_FS=y
# CONFIG_EXT2_FS_XATTR is not set
CONFIG_EXT3_FS=y
CONFIG_EXT3_FS_XATTR=y
# CONFIG_EXT3_FS_POSIX_ACL is not set
# CONFIG_EXT3_FS_SECURITY is not set
CONFIG_JBD=y
# CONFIG_JBD_DEBUG is not set
CONFIG_FS_MBCACHE=y
# CONFIG_REISERFS_FS is not set
# CONFIG_JFS_FS is not set

#
# Pseudo filesystems
#
CONFIG_PROC_FS=y
CONFIG_PROC_KCORE=y
CONFIG_SYSFS=y
# CONFIG_DEVFS_FS is not set
# CONFIG_DEVPTS_FS_XATTR is not set
# CONFIG_TMPFS is not set
# CONFIG_HUGETLB_PAGE is not set
CONFIG_RAMFS=y


That?s all i think.

Best regards,

David

Re: AW: AW: AW: initrd rootfs ramdisk

[T Ziomek]

On Thu, 21 Jul 2005, David Grab wrote:
>
>>> i solved my problem with u-boot and linux. Now i have my rootfs ramdisk
>>> mounted and functioning. But one output is weird.
>
>> Can I ask what what you had to change to get your initrd RAM disk working?
>> I'm having a very similar problem.
>
> Sure! :)

Sigh...found it, after weeks of on-and-off work...  Our board has 64 MB of
RAM but I'm passing "mem=32M" to the kernel because we want our app to man-
age the high 32 MB.

U-Boot defaults to copying an initrd into the highest available RAM.  That
put it in an area outside of Linux's knowledge, D'OH.  All I had to do was
set U-Boot's 'initrd_high' env var and things work.

Thanks for the info anyway; I've saved it.
Tom

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Re: AW: AW: AW: initrd rootfs ramdisk

[Wolfgang Denk]

In message <Pine.WNT.4.61.0507211609080.2672@holyoke.labs.mot.com> you wrote:
>
> Sigh...found it, after weeks of on-and-off work...  Our board has 64 MB of
> RAM but I'm passing "mem=32M" to the kernel because we want our app to man-
> age the high 32 MB.
> 
> U-Boot defaults to copying an initrd into the highest available RAM.  That
> put it in an area outside of Linux's knowledge, D'OH.  All I had to do was
> set U-Boot's 'initrd_high' env var and things work.

Note: if you want the  content  of  this  reserved  area  to  survice
warmboots  you  can  enable  the  "protected  RAM"  feature in U-Boot
(CONFIG_PRAM), and it will not touch this area  at  all.  Useful  for
things like pramfs for example :-)

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
Never worry about theory as long as  the  machinery  does  what  it's
supposed to do.                                      - R. A. Heinlein