5 ways to reboot a PC. None of them reliable.

nuclear_eclipse wrote: post #2

It amazes me that this sort of behavior still hasn't been standardized and agreed upon by all PC and component manufacturers.

Reality is that in areas of poor standardisation, vendors will test against Windows and ship it if it works. You could argue for a cross-vendor compliance testing suite, but if the behaviour of Windows varied from that then people would still need to match the Windows behaviour because that's where the market is.

So for all practical purposes, the behaviour is standardised. It's just embodied in the behaviour of Windows rather than anywhere useful.

Re: 5 ways to reboot a PC. None of them reliable.

#5

Post by wzdd » Wed, Jun 01, 2011, 2:41 PM UTC

Method 6: return to 16-bit mode, call interrupt 0x19 (not if you're on efi).

Method 7: return to 16-bit mode, set cs to 0xf000 and jump to 0xfff0.

Linux used to use method 6, but it wasn't reliable either. Something tells me returning to 16-bit mode might not be possible for some hardware / driver combinations.

Re: 5 ways to reboot a PC. None of them reliable.

#6

Post by mjg59 » Wed, Jun 01, 2011, 2:53 PM UTC

wzdd wrote: post #5

Method 6: return to 16-bit mode, call interrupt 0x19 (not if you're on efi). Method 7: return to 16-bit mode, set cs to 0xf000 and jump to 0xfff0. Linux used to use method 6, but it wasn't reliable either. Something tells me returning to 16-bit mode might not be possible for some hardware / driver combinations.

Method 7 is available for 32-bit systems, and actually pretty reliable. But going from 64-bit to 16-bit just to reboot is more pain than anyone really wanted to go through.

Re: 5 ways to reboot a PC. None of them reliable.

#7

Post by michael_dorfman » Wed, Jun 01, 2011, 2:54 PM UTC

lebug wrote: post #3

Just type SYS 64738.

Wow, that takes me back. Nicely done.

Re: 5 ways to reboot a PC. None of them reliable.

#8

Post by chadgeidel » Wed, Jun 01, 2011, 2:58 PM UTC

Wow - that's very interesting. So, what do most operating systems (aside from Apple presumably) normally do to get a consistent reboot?

Are they probing the hardware at install time? Do they just have a "table of things to try" the first time you reboot and then use the "successful thing" from then on?

Re: 5 ways to reboot a PC. None of them reliable.

#9

Post by rbanffy » Wed, Jun 01, 2011, 3:39 PM UTC

Was there ever a computer as ugly as the IBM-PC?

I imagine even the Commodore 16 could reboot itself reliably.

Re: 5 ways to reboot a PC. None of them reliable.

#10

Post by mjg59 » Wed, Jun 01, 2011, 3:50 PM UTC

chadgeidel wrote: post #8

Wow - that's very interesting. So, what do most operating systems (aside from Apple presumably) normally do to get a consistent reboot? Are they probing the hardware at install time? Do they just have a "table of things to try" the first time you reboot and then use the "successful thing" from then on?

Most operating systems fail on various bits of hardware. Windows uses the ACPI vector, then tries the keyboard controller, then the ACPI vector again, then the keyboard controller again, and then just stops.