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INT 15.87 in protected mode (Developers)

posted by RayeR Homepage, CZ, 09.09.2011, 01:51
(edited by RayeR on 09.09.2011, 02:17)

> There are two "parts" to ACPI. Part of it is stored in fixed-format
> tables, and part of it is more "free-form" (this includes the AML part).
> Nothing in ACPI is trivial, but the fixed-format part is not too difficult
> to wade through. The details on how to change the CPU duty cycle and how
> to shut down the computer are in the fixed-format part.
Well, could you tell me e.g. what can I read from fixed tables about modifying CPU duty cycle? How ACPI describe it? Will I read some IO port address or memory address and description what data to write in? I though that you have to run AML code for that but if not then it would be easier...

> The "free-form" part is another matter altogether. AML in particular is
> EXTREMELY nasty. Unfortunately, determining the number of CPU's must be
> done by parsing the free-form part, though it is not AML, so I think it
> could be done without too much difficulty (famous last words, since I've
> never actually done it).
I'll see. ACPI spec has many many pages... :P

> It's definitely not as easy as figuring out how to shut down the computer.
Some years ago I made an utility that can shutdown PC in a hard way by programming some PCI registers of ICH via SMBus. It's quite simle:

#define SMB_ICH_SLAVE       0x44       // 1000100 - ICH SMB Slave port
#define ICH_SLAVE_CMD_REG          0   // reg. 0 - Command Register
#define ICH_SLAVE_WAKEUP_CMD       1   // 0x01 - WakeUp if is in sleep state
#define ICH_SLAVE_PWRDOWN_CMD      2   // 0x02 - Unconditional Powerdown
#define ICH_SLAVE_HWRESET_CMD      3   // 0x03 - Hardware Reset without power off/on
#define ICH_SLAVE_HWRESETOFFON_CMD 4   // 0x04 - Hardware Reset with power off/on
#define ICH_SLAVE_WDRELOAD_CMD     6   // 0x06 - WatchDog timer Reload

smb_write8(SMB_ICH_SLAVE,cmd,ICH_SLAVE_CMD_REG);


http://rayer.ic.cz/programm/pwrdown.exe

> The other thing to keep in mind is that at least some computers store bogus
> information in ACPI, so you can't necessarily believe what it tells you.
Yes, also windows and linux denied to use ACPI on some old PC but I belive it's clean now.

---
DOS gives me freedom to unlimited HW access.

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