File system boot strategy

File system boot strategy

[Gérard Guével]

Hi,

I have a custom 8260 board with a 2.4.18 Kernel.

I want to mount multiple file systems from a CFI compliant flash.
The directories are distributed  like this :

	/   /bin /home /lib /root /sbin /usr		-> cramfs  to have a protected Linux
kernel
	/etc /tftpboot				-> jffs2      to allow modifying services and files to
load
	/dev /proc /tmp /var			-> ramfs    to store data which can be lost.

I want to boot with the cramfs as root file system but the UNTAR wants all
the directories /dev /proc /tmp in the cramfs.

Can I use multiple file systems like this ?
Must I start with a ramfs and then mount cramfs ?

I find many docs to mount each file system individually and to add others
file systems mounted on /mnt
but no example to break a standard filesystem into multiple sub file
systems.

Any help would be welcome.

Thanks
Gérard Guével


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Re: File system boot strategy

[Gary Thomas]

On Fri, 2003-11-14 at 05:57, Gérard Guével wrote:
> Hi,
>
> I have a custom 8260 board with a 2.4.18 Kernel.
>
> I want to mount multiple file systems from a CFI compliant flash.
> The directories are distributed  like this :
>
> 	/   /bin /home /lib /root /sbin /usr		-> cramfs  to have a protected Linux
> kernel
> 	/etc /tftpboot				-> jffs2      to allow modifying services and files to
> load
> 	/dev /proc /tmp /var			-> ramfs    to store data which can be lost.
>
> I want to boot with the cramfs as root file system but the UNTAR wants all
> the directories /dev /proc /tmp in the cramfs.
>
> Can I use multiple file systems like this ?
> Must I start with a ramfs and then mount cramfs ?
>
> I find many docs to mount each file system individually and to add others
> file systems mounted on /mnt
> but no example to break a standard filesystem into multiple sub file
> systems.

There is nothing special about /mnt - it's just a directory (or set of
directories like /mnt/floppy, /mnt/cdrom, etc). Also, the main names
(like /etc) could be symbolic links.  Here's how I might solve this:

==  cramfs  contents

    /bin
    /home
    /lib
    /root
    /sbin
    /usr
    /JFFS2          (just a mount point)
    /etc => /JFFS2/etc
    /tftpboot => /JFFS2/tmp
    /RAMDISK        (another mount point)
    /tmp => /RAMDISK/tmp
    /var => /RAMDISK/var

/dev and /proc are special.  If you enable "devfs" and "procfs" in the
kernel they get populated automatically, all you need do is mount them.

--
Gary Thomas <gary@mlbassoc.com>
MLB Associates


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MPC8260 HDLC RX length errors

[Gérard Guével]

Hi,

I work on a custom 8260 board and a 2.4.18 Kernel
with an HDLC driver on SCCs ports.

I want to limit the frame length to 1501,
so I use the mflr register :

volatile scc_hdlc_t *hp     = (scc_hdlc_t *)chan->mem_start;
...
/* set the MTU */
hp->mflr = chan->conf.hdlc_hdl_conf.hdlc_mtu;
...

The driver works fine with all frames lower than 1501.

When the CPM receives a frame of 1502 characters, it
closes the buffer descriptor with a BD_HDLC_RX_LG error.
That's right but all the following frames with a right
length (< 1501) are rejected with the same BD_HDLC_RX_LG error.

The BD flags are correctly erased after each error
and new buffers are provided to the CPM.

The problem is not bound to the frame rate.

Any idea

Thanks
Gérard Guével


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