Subject: RE: memory based root filesystem
To: None <,,>
From: Jared Momose <>
List: tech-kern
Date: 01/10/2005 14:45:40

For a root memory disk you need to include the kernel option "pseudo-device 
md" as opposed to "file-system MFS". Also, when you build your memory disk, 
be conscious of the endianness used by makefs (specified by the -B option). 
When developing on systems with different endianness, compiling both host 
and target kernels with "options FFS_EI" (endian independence) might not be 
a bad idea.

Best regards,

>  I configured the kernel as per the link here;-
>I find that mount_ffs fails with errno 79. I have
>enabled both MFS and FFS in the config file. Attached
>below is the output. Also, the bootup mechanism does
>not allow me to select mfs (generic, ffs, halt,
>reboot)  Can someone help with setting root to RAM?
>pasted below output from bootup.
>switching to new L1 page table
>@0xa01fc000...bootstrap done.
>init subsystems: stacks vectors undefined page pmap
>Copyright (c) 1996, 1997, 14
>     The NetBSD Foundation, Inc.  All rights reserved.
>Copyright (c) 1982, 1986, 1989, 1991, 1993
>     The Regents of the University of California.  All
>rights reserved.
>NetBSD 2.0 (TRITON) #48: Mon Jan 10 14:21:36 EST 2005
>total memory = 16384 KB
>avail memory = 8708 KB
>mainbus0 (root)
>cpu0 at mainbus0: PXA250 rev 6 (XScale core)
>cpu0: DC enabled IC enabled WB enabled LABT branch
>prediction enabled
>cpu0: 32KB/32B 32-way Instruction cache
>cpu0: 32KB/32B 32-way write-back-locking Data cache
>pxaip0 at mainbus0: PXA2x0 Onchip Peripheral Bus
>pxaip0: CPU clock = 99.527 MHz
>pxaintc0 at pxaip0 addr 0x40d00000-0x40d0001f:
>Interrupt Controller
>pxagpio0 at pxaip0 addr 0x40e00000-0x40e0006f: GPIO
>com0 at pxaip0 addr 0x40100000-0x4010001f intr 22:
>ns16550a, working fifo
>com0: console
>saost0 at pxaip0 addr 0x40a00000-0x40a0001f
>saost0: SA-11x0 OS Timer
>clock: hz=100 stathz = 64
>md0: internal 4096 KB image area
>cpu_lwp_fork: 0xc07214d4 0xc2a42000 0xc07214d4
>l1->procaddr=0xc01ed000 l1->procaddr->u_pcb=0xc01ed000
>pid=1 pmap=0xc07250e4
>l2->procaddr=0xc2a38000 l2->procaddr->u_pcb=0xc2a38000
>pid=1 pmap=0xc2a41000
>boot device: <unknown>
>root on md0a dumps on md0b
>no file system for md0 (dev 0x1200)
>cannot mount root, error = 79
>root device (default md0a):
>dump device (default md0b):
>file system (default generic): ffs
>root on md0a dumps on md0b
>cannot mount root, error = 22
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