[Qemu-devel] How to Simulate hardware that counts scanlines?

[Qemu-devel] How to Simulate hardware that counts scanlines?

[Steve Ellenoff]

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[Qemu-devel] Adding a device into Qemu ARM

[Tieu Ma Dau]

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Hi all,
 I'm running Qemu ARM system and Debian Sarge on it.
 I try to add a new device, for example a LED, into Qemu ARM system. And I think that I must do the following steps:
 1. Make a file led.c which simulates this LED, edit the file vl.c and vl.h
 2. In file integratorcp.c, function integratorcp_init(), I must register a MEMORY SPACE for this LED (as the PL011 UART at 0x16000000)
 3. Write a character device driver; this device driver will function on the MEMORY SPACE of the LED device. And this device driver has a MAJOR NUMBER
 4. Make a character device file with the corresponding MAJOR NUMBER: mknod /dev/my_LED c MAJOR_NUMBER 0
 5. Write an application which opens the file /dev/my_LED and write on it (to communication with my LED on Linux)
 OR: for example "echo -n a > /dev/my_LED" to communication with my LED on Linux
 
 I find that some of you who added the devices into Qemu ARM system, but I don't sure the steps I think above is as you 've done or not? Please confirm it for me, thank a lot!
 
 Furthermore,  I have some questions on the steps above:
 + step 2: which interrupt I can register with the PIC? Or in my case, it must not?
 + step 2: which value of MEMORY SPACE I can register for this LED?
 Best regards,
 Tieu
 
 		
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Re: [Qemu-devel] Adding a device into Qemu ARM

[Paul Brook]

>  Furthermore,  I have some questions on the steps above:
>  + step 2: which interrupt I can register with the PIC? Or in my case, it
> must not? 
> + step 2: which value of MEMORY SPACE I can register for this 
> LED?

Anything that's not already being used. Same way you would if you were 
designing real hardware.

Paul

Re: [Qemu-devel] How to Simulate hardware that counts scanlines?

[André Braga]

On 7/27/06, Steve Ellenoff <sellenoff@hotmail.com> wrote:
> The guest os code is polling this register on a very fast interval, and when
> it detects a certain # of scanlines have been counted, it will swap it's
> display buffers, ie, it's waiting for the vblank, so it can have nice smooth
> animations.

Since this is all custom, I'd rather raise an interrupt when the DAC
reaches the final portion of the frame buffer... This has to be better
than polling.