Re: DVORAK and ro

[cloudmaster <cloudmaster@cloudmaster.com>]

Jeff Licquia wrote:
> On 30 Apr, Cloudmaster wrote:
> One thing I've seen with read-only filesystems: use a ramdisk for root.
> There's a HOWTO for that somewhere, as I recall.  It sucks lots of
> memory, but memory is cheap these days, and with fancy symlinking you
> can probably trim down the requirements.  If you use something like
> Tom's for a base system, you could do very well with an 8MB ramdisk.

I think I'm gonna keep the stripped down SuSE 5.3 (it's what I had) for now
- it's around 50 MB - and then in a while when I go with a new hard drive
I'll build my own, either based on one of those rescue systems or out of
nothing (depending on my ambition level)...  For now, I'll just leave all
those libraries I don't need in there with the others.

...
> I remember that the empeg guy (the guy now working on building car MP3
> players) was talking about this problem somewhere.  I can't remember
> his exact solution, but I remember reading about a root ramdisk system
> (see above), as well as some kind of capacitor and a sensor attached to
> the ignition.  The former system would simply cut power immediately to
> the system, while the latter relied on careful measurement of how long
> it takes to remount all disks read-only (sensor flags power-off
> situation, daemon immediately kills all MP3 player processes and
> remounts necessary disks read-only, & we all hope that the capacitor
> has enough juice).

I figured out a way to set it up so that ignition turning on will start it
up, and when the computer's running to just set a pin on a serial port high
(or parallel, I haven't decided yet).  If I had an ATX supply, that'd b
even better, because I could just use one of the +5 leads on the PS to tell
when the computer's on.  Anyway, I'm doing up something similar to the UPS
daemons to poll the RX pin on the serial port for a connection.   When the
ignition loses power, it starts the shutdown sequence.  When the
"computer-on" lead goes low, it shuts of a relay and kills the inverter's
power.  It's really kinda cool...  Initially I had a circuit drawn up using
a few AND's and a couple inverters, but later I looked closer and realized
I only needed a single OR.  I'll get a circuit diagram up at
http://www.cloudmaster.com/cloudmaster/cdproject in a few days. :)

--Danny, who should be listening to it by this weekend

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