[Fwd: Re: kernel command line for CRAMFS root filesystem]

-------- Original Message --------
Subject: Re: kernel command line for CRAMFS root filesystem
Date: Thu, 06 Jun 2002 16:40:33 +0200
From: Julien Eyries <redacted>
To: acurtis@onz.com
References: [off-list ref]


i have never mounted it before .

i am currently booting with initrd (good :-)) from my flash and it works
fine( the commandline was : root=/dev/rd/0 );
but now i want to replace that with a cramfs (better :-)) .

anyway, i know i can acess to the range (start 0xfe100000 - length
2MBytes) via my partition /dev/mtdblock/2 but if i try something like :
   root=/dev/mtdblock/2 then JFFS2 try to mount it as root filesystem and
fails !!!!!!

maybe i should add something to the commandline, in order to tell the
kernel that /dev/mtdblock/2 contains a CRAMFS partition ??






Allen Curtis wrote:

 >>i have a cramfs image in flash, at address 0xfe100000 (length of image
 >>is 2MBytes).
 >>what is the kernel command line "root=..." to use this image as root
 >>filesystem ?
 >>
 >
 > What is the device name when you mount it from a bootp session? The
name is
 > probably the same...
 >
 >


--
Julien Eyries
R&D engineer
Thales Broadcast & Multimedia (ex-thomcast)
email: julien.eyries@thales-bm.com
fax: 33(0) 1 34 90 31 10
tel: 33(0) 1 34 90 31 01





--
Julien Eyries
R&D engineer
Thales Broadcast & Multimedia (ex-thomcast)
email: julien.eyries@thales-bm.com
fax: 33(0) 1 34 90 31 10
tel: 33(0) 1 34 90 31 01


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Hello,

i have never mounted it before .

maybe you should try it from shell first to see if the cramfs is ok.

i am currently booting with initrd (good :-)) from my flash and it works
fine( the commandline was : root=/dev/rd/0 );
but now i want to replace that with a cramfs (better :-)) .

anyway, i know i can acess to the range (start 0xfe100000 - length
2MBytes) via my partition /dev/mtdblock/2 but if i try something like :
   root=/dev/mtdblock/2 then JFFS2 try to mount it as root filesystem and
fails !!!!!!

maybe i should add something to the commandline, in order to tell the
kernel that /dev/mtdblock/2 contains a CRAMFS partition ??

we use cramfs here and it works without additional parameter. How do you
generate the cramfs and on which kind of system are you using it? The
mkcramfs tool has an endianess problem so if you do mkcramfs on 86x platform
to use it on ppc it wont work. (maybe there is some newer version i am not
aware of where that is fixed)

Hope that helps,
good luck and best regards,
Michael


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

we use cramfs here and it works without additional parameter. How do you
generate the cramfs and on which kind of system are you using it? The
mkcramfs tool has an endianess problem so if you do mkcramfs on 86x platform
to use it on ppc it wont work. (maybe there is some newer version i am not
aware of where that is fixed)

Well it seems it is the problem ... i have generated cramfs on my x86
and my target is ppc .
is there a simple trick to make my cramfs image correct for ppc ?
should i build my cramfs image on the target ?

thanks,

Julien.


details
-------
ok i boot my target over nfs, and i try to mount my cramfs with :

# mount -t cramfs /dev/mtdblock/2 /mnt/temp
wrong magic
......

# dd if=/dev/mtdblock/2 of=/root/toto.dat bs=1024 count=1


then i switch to my PC (x86) to look at what i have :

#hexdump /root/toto.dat | more
0000000 3d45 28cd 0000 0001 0000 0000 0000 0000
0000010 6f43 706d 6572 7373 6465 5220 4d4f 5346
0000020 6344 2423 98f1 b87f daf3 58a0 b74a a046
0000030 6f43 706d 6572 7373 6465 0000 0000 0000

in cramfs.h :
#define CRAMFS_MAGIC		0x28cd3d45	/* some random number */



--
Julien Eyries
R&D engineer
Thales Broadcast & Multimedia (ex-thomcast)
email: julien.eyries@thales-bm.com
fax: 33(0) 1 34 90 31 10
tel: 33(0) 1 34 90 31 01


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Hi Julien,

Attached is a patch to mkcramfs that adds a "-r" option.  This
reverses the endianness of the CRAMFS filesystem when creating it.
I use this patched mkcramfs to do exactly what you are doing.
It should apply to all kernels up to and including 2.4.18.

Steve


Julien Eyries wrote:

quoted

we use cramfs here and it works without additional parameter. How do you
generate the cramfs and on which kind of system are you using it? The
mkcramfs tool has an endianess problem so if you do mkcramfs on 86x platform
to use it on ppc it wont work. (maybe there is some newer version i am not
aware of where that is fixed)

Well it seems it is the problem ... i have generated cramfs on my x86
and my target is ppc .
is there a simple trick to make my cramfs image correct for ppc ?
should i build my cramfs image on the target ?

thanks,

Julien.

--
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