[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-discuss] QEMU and reboots via 0xcf9

From: Dipanjan Das
Subject: Re: [Qemu-discuss] QEMU and reboots via 0xcf9
Date: Fri, 28 Dec 2012 14:27:13 +0530

On 28 December 2012 00:03, Jakob Bohm <address@hidden> wrote:
On 12/27/2012 7:08 PM, John Floren wrote:
I'm working on an OS kernel that currently reboots by writing 0x02,
then 0x06 to port 0xcf9. This seems to work fine for real hardware,
but I have not been able to make it work in QEMU. Before I go digging
through the QEMU source to try and verify one way or another, I
thought I'd ask here: Can I use 0xcf9 to reboot on QEMU?

Try the technique documented here.

Where did you pick up that technique?

Looking in an old PC manual, I see that port 0x0f9 (often, only low 10
bits were decoded) is in the range of ports used for talking to the
80x87 coprocessor, which has long since been replaced by native x87
instruction support inside the CPUs, so I am quite unsure what is
supposed to be responding to I/O port 0xcf9 on a real PC.


Jakob Bohm, CIO, Partner, WiseMo A/S.  http://www.wisemo.com
Transformervej 29, 2730 Herlev, Denmark.  Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded


Thanks & Regards,


reply via email to

[Prev in Thread] Current Thread [Next in Thread]