hey check out my crappy iso :)

Thomas Krennwallner technik at e-moritz.at
Tue May 8 04:20:54 PDT 2001


On Tue, May 08, 2001 at 04:44:02AM +0000, the boisterous Bryan Dumm <bryan at bcpub.com> wrote:
> Ok, I am going to throw another log on the fire, Tmpfs.... mmmm
> 
> Tmpfs I guess is what ramfs is moving to... Below are the details.
> I believe like with ramfs, you can keep on mounting as many different
> ramfs(er tmpfs) mount points as you need ie...

tmpfs looks ideal for /tmp and /var.

> mount -t ramfs ramfs /etc
> mount -t ramfs ramfs /tmp
> mount -t ramfs ramfs /sbin
> 
> With tmpfs it also looks like you can have not only limits, but 
> dynamic ones. The question still remains though, should one
> 
> cp -a /etc /etc
> 
> after a mount ramfs(overlapping), and how does that work?
> Wouldn't you have to do it before hand, like copying it into 
> memory to umm, put it back into memory? :) 
>  

I looked at your prev. mail and now I have the solution (it was too early for
me, just stood up ;-).

this cp doesn't work -> from where to where -> if you "overmount" something,
the previous content is hided (until umount).

so overmount with ramfs will work something like that:

mount -t ramfs ramfs /ramfs
cp -a /etc/* /ramfs
mount -t ramfs ramfs /etc
mv /ramfs/* /etc
.
. other dirs for overmounting
.
umount /ramfs

this looks like an overhead (two cp/mv) but I think its easier to maintain than
tarball the stuff needed for ramfs'ing.

and in the future, when /etc can be ro, I consider something like this:
devfs /dev  devfs defaults 0 0
tmpfs /tmp  tmpfs defaults 0 0
tmpfs /var  tmpfs defaults 0 0 # this needs some patching for subdirs
proc  /proc proc  defaults 0 0
usbdevfs /proc/bus/usb defaults 0 0

so no special handling (except /var) is needed for the mounting problem in a
cd-rom environment. And if you need a rw /etc (perhaps network installation ->
/etc/resolv.conf and so on), it can be handled like /var.

I see with 2.4, Linux is much more dynamic in terms of fs. It simplifies the
handling of rw directories and enables powerful embedded systems.

And after checking some stuff, tmpfs == shmfs, or?

so long
Thomas

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