Patryk Zadarnowski writes:
>> Mark Hittinger writes:
>> >
>> >Something that the old DEC took a few stabs at was the idea of a
>> >"checkpoint" feature where a process or a series of processes could be
>> >put in a quiesced state. This would page out the process or processes
>> >into the swap space, allow a hardware shutdown, and after a reboot allow
>> >the restart of the checkpointed process(es).
>> >
>>
>> I did something like this for Philips while I was at UniSoft. It
>> depended on some special hardware features (turning off/losing power
>> generated an interrupt, there was a small UPS in the box along with
>> battery-backed SRAM to save various kernel structures).
>>
>> Turning off the power caused all memory to be saved to disk (the kernel
>> turned off the UPS after it was done). Upon a restart the kernel noticed
>> that memory had been saved, read the contents in from disk, futzed around
>> with some structures, and restarted what was curproc at the time of
>> shutdown. It even worked ;-)
>>
>> Philips never did anything with it.
>
>Out of pure curiosity, what did you do with pending interrupts, partially
>completed DMA transfers and other such state information?
>
IIRC (this was all 13 years ago) there were hooks in the drivers
which were called on shutdown/startup so that they could DTRT.
I do remeber that some characters were lost on the serial ports.
Disk and network seemed to work fine, though.
---
Gary Jennejohn / [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED]
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