Uncompressed root fs to ramdisk.

[Kyle Harris]

Ralph,

I found that I can remount / read-only after mingetty runs and
everything works fine. No more errors when trying to spawn mingetty on a
write only device. Once they're open it appears making them ro has no
effect. I added the following line to the very end of /etc/inittab.

tk:23:once:/bin/mount -n -o remount,ro /

Ralph Stickley wrote:
> 
> Kyle,
> Thanks for the help!
> 
> --- Kyle Harris <kharris@nexus-tech.net> wrote:
> > Ralph,
> >
> > Please see below.
> >
> > Ralph Stickley wrote:
> >
> > > Not sure about the minigetty thing.  I think the /dev/tty things (are they
> > > files , pipes ? does anybody know ?? ) have to be in R/W partition. I just
> > > linked to my ram disk:
> >
> > /dev/xxx are special "files" called nodes. It provides a mechanism for
> > accessing devices through a major and minor number.
> >
> Ahhh! thats the mknod thing does ... Still not sure how the permissions
> get changed on these files even with a read-only file system...
> 
> Of course, init finds rc.sysinit before I execute a mount...
> 
> Hey, does the kernel mount the "root=/dev/hdx" device specified to Lilo?
> Then it can read inittab and use the /dev stuff.  Then rc.sysinit
> mounts this as read only.
> Only guessing here, then why doesn't my initial console work ?
> Does this mean my file system is mounted read/write at boot time ?
> 
> Hmmmm...I guess I'd have to study the kernel source code to find this...
> any clues ?
> 
> > >
> > > mount /dev/ram /var
> > > /tmp -> /var
> > > /dev/tty0 -> /tmp/tty0
> > > ...
> > >
> >
> > I like this idea of having /dev in the ramdisk.
> 
> Only some items are linked...others seem to work even though they are in
> read only file system...(like /dev/ram :)
> 
> > But how does this work
> > since you need /dev/ram in order to create and mount /var? And the
> > kernel wants a console early in the boot sequence.
> >
> 
> Oops...caught me :-)  I get a nasty message from the kernel at boot time.
> Something about not being able to open initial console. Ok. Tough! Hmmmm...
> wonder if that screws up other stuff ??  I have no clue whats going on
> here with these /dev/ node things...
> 
> > > Where /tmp is a link to the /var mount point for the ram disk. That might
> > help
> > > ?
> > >
> > > Do you create more than one ramdisk ? How do you specify the size of your
> > ram
> > > disk ?
> >
> > for a 2 MB disk, I use mke2fs -m0 /dev/ram0 2048
> >
> Ah...another flag!  Should have figured..Thanks for the help :-)
> 
> Later,
> Ralph
> 
> > Kyle.
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