Subject: memory disk, evbarm - lubbock
To: '' <>
From: Stewart Heitmann <>
List: tech-kern
Date: 04/14/2003 15:42:29
I am trying to create a memory disk within the kernel
for the evbarm port to the LUBBOCK (Intel XScale) eval board.
Ultimately I want to put the root filesystem on the memory disk,
but havent got that far yet because I cant make the memory
disk large enough.

I can compile a kernel with up to 4096K space set aside
for the memory disk, but when I try to make it larger I
get a kernel panic. 
Oddly enough, when I make it much much larger (16384K or more)
the kernel boots ok, but /sbin/init seg faults.

Is there a limit on the size of a memory disk?
I'd like to make one about 30MB, is that a silly thing to try???

For the record, my kernel config has:
	options 		MEMORY_DISK_HOOKS			#
boottime setup of ramdisk
	options		MEMORY_DISK_SERVER=0   		# no userspace
memory disk support
	#options 		MEMORY_DISK_IS_ROOT		# use memory
disk as root (disabled for now)
	options           MEMORY_DISK_ROOT_SIZE=8192 	# (md0=4096K)

	# disk/mass storage pseudo-devices
	pseudo-device	md		1			# memory
disk device (ramdisk)

My config file has other options that no longer seem to have any effect,
and I cant find any reference to them in sys/dev so I believe they are
redundant. Can anyone confirm these are no longer required?
	#options 	MEMORY_DISK_SIZE=3072	# Size in blocks
	#options 	MINIROOTSIZE=1000		# Size in blocks

Anyone got any ideas?

I originally posted to but got no response
other than a sympathetic sigh from somebody else having with the same

Stewart Heitmann <>