configuring swap on a diskless mpc860 embedded target

configuring swap on a diskless mpc860 embedded target

[Jim Chapman]

Is anyone using an NFS-mounted swap file on an mpc860 diskless system?

I created a swap file on the embedded target using

dd if=/dev/zero of=/SWAPFILE bs=1k count=8192
mkswap /SWAPFILE

But when I try to enable swapping using "swapon /SWAPFILE", linux
complains that it can't find a swap signature in the file. I've looked
at the file using a hex dump and it seems to be in the right place (10
characters at offset 4096-10). Adding some debug printk's, I can see
that sys_swapon() reads in random data (usually NULLs, but not always)
into a swap_header struct. I get the same result with v0 and v1 swap
file formats.

I tried creating the swap file on my PowerMac G3 (running linux-2.2.10)
but that yielded the same result.

My kernel is the embedded 2.2.13 running on a custom mpc860 board. The
system's NFS root is served from a cheapie x86 system running
linux-2.2.13.

Any thoughts?

-Jim


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Re: configuring swap on a diskless mpc860 embedded target

[Dan Malek]

Jim Chapman wrote:
> 
> Is anyone using an NFS-mounted swap file on an mpc860 diskless system?


Ummm...no.....That's not very high on the list, as embedded
products don't usually swap.....

I don't know much about swapping, except that all of the
systems I have will use an exclusive disk partition for that.
There may be some assumptions in the code about underlying
media....


	-- Dan

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Re: configuring swap on a diskless mpc860 embedded target

[Kenneth Johansson]

A question:
    Have you ever swapped over nfs on any linux system?  I don't think it
works.

The only way I know of is using the network block device and a patch to make
swapping over that work.


Jim Chapman wrote:

> Is anyone using an NFS-mounted swap file on an mpc860 diskless system?
>
> I created a swap file on the embedded target using
>
> dd if=/dev/zero of=/SWAPFILE bs=1k count=8192
> mkswap /SWAPFILE
>
> But when I try to enable swapping using "swapon /SWAPFILE", linux
> complains that it can't find a swap signature in the file. I've looked


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Re: configuring swap on a diskless mpc860 embedded target

[Leif Lindholm]

KJ> A question:
KJ>     Have you ever swapped over nfs on any linux system?  I don't think it
KJ> works.

KJ> The only way I know of is using the network block device and a patch to make
KJ> swapping over that work.

There was a patch for this for the 2.0.2x kernels.

It is available at http://www.vu.union.edu/~hagopiar/linuxnfsswap/ if
someone would like to upgrade it.

regards
/
       Leif


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