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#92 - 08/07/1999 04:14 System crashes and other bits.

Registered: 08/07/1999
Posts: 35
I have a couple fo questions... appolgies if they've been asked before...

1) I know the player runs Linux (which is a lot more reliable than some OS's), but I was wondering what would happen if you were out on the road playing some tunes and the system crashes. Would you be stuck until you get home again? Is there a certain sequence of key presses to reboot the system and auto-login so you can start the music again? Some other contingency plan?

2) I read a post from Hugo (I think it was on /.) that said there wouldn't be a problem with the disk problems etc when you turn the ignition off, when you turn the ignition back on it would resume from the point you turned off... how? Is the system running permanently from the car battery?



- Given two theories.... pick the one that sounds funniest -
- Given two theories.... pick the one that sounds funniest -

#93 - 08/07/1999 09:25 Re: System crashes and other bits. [Re: 0sb0rne]
carpal tunnel

Registered: 10/06/1999
Posts: 5900
Loc: Wivenhoe, Essex, UK
I assume that it will work in a similar way to Hugo's own MP3 Mobile. The
unit will have power to it at all times, but will only power up the CPU,
harddisks, DSP etc when it needs to.
I imagine it will go like this:
1. You turn the ignition
2. Some hardware (not software) in the unit detects this
3. The CPU and hard drive are powered up
4. Linux boots from the flash RAM
5. The software reads the disk to find out where to resume from
6. The unit reads the next MP3 file in to RAM, spins down the hard disk and
starts playing

When you turn of the ignition the following probably happens:

1. You turn off ignition
2. Hardware in unit detects this and sends a signal to Linux (probably via
the serial interface)
3. Linux is given say 10 seconds to shutdown
4. As part of this shutdown the empeg software writes the resume position to
the hard disk
5. At the end of the 10 seconds whether Linux has shutdown properly or not
the unit removes power from the CPU and hard disk

This means to reset after a crash you just have to power the unit off.

I wouldn't be surprised to find our that the unit also makes use of the
watchdog module in Linux to reboot the system automatically if it has hung.

Number 330 in the queue...
Remind me to change my signature to something more interesting someday

#94 - 08/07/1999 15:02 Re: System crashes and other bits. [Re: andy]
carpal tunnel

Registered: 19/05/1999
Posts: 3457
Loc: Palo Alto, CA
In fact, the unit doesn't work like this. It has no permanent battery feed, and will save where it is even if you yank it out of the dash when playing. Basically, it monitors the input voltage to the PSU. If this drops below 10v, a powerfail interrupt is generated which causes the current state information to be saved to a page in flash rom (it cycles these - you'll get at least a million saves before the flash wears out).

When it boots is checks the flash for the latest valid saved position data and continues from this point (the actual playlist is saved to a hard disk partition when a new playlist is generated/selected, as this is too big to be saved on a power fail).