Petazzoni Thomas thomas.petazzoni at ifrance.com
Thu Apr 6 18:13:33 CEST 2000

Hi everybody,

This has not much to do with the OpenBIOS project, but with low level
programming. Everyone here seems to know lot of things in this domain,
that's why i'm asking to all of u those questions :

1. Can we setup a VESA 2 (not VESA 3 !) configuration (select video
mode, and everything) without making a int 0x10 ? We're programming a
protected mode OS, and switching to VM86 sucks. I know it's possible
with VESA 3, but with VESA 2 ?
If yes, do you have any docs about it ?
Is the int 0x10 VESA code specific to each graphic card ?

2. I've got a problem with DMA programming, here's my source :

const static DmaChannel dmainfo[] = {
  { 0x87, 0x00, 0x01 },
  { 0x83, 0x02, 0x03 },
  { 0x81, 0x04, 0x05 },
  { 0x82, 0x06, 0x07 }

void dma_transfer(int channel, long physical_address, unsigned int
length, unsigned sh
ort read) {

  long page, offset;

  if(channel >= 4)
     printk("\nThis function does to manage with channel 4, 5, 6, 7");
     return ;

  page = physical_address >> 16;
  offset = physical_address & 0xFFFF;
  length -= 1;

  // DIsable IRQs
  outb(0xFF, 0x21);
  outb(0xFF, 0xA1);

  // Masking channel (disable)
  outb(channel | 4, 0x0A);
  // Reset Flip-Flop
  outb(0, 0xC0);

  // Mode
  outb( (read ? 0x48 : 0x44) | channel, 0x0B);
  // Page
  outb(page, dmainfo[channel].page);

  // Offset
  outb(offset & 0xFF, dmainfo[channel].offset);
  outb((offset >> 8) & 0xFF, dmainfo[channel].offset);

  // Length
  outb(length & 0xFF, dmainfo[channel].length);
  outb((length >> 8) & 0xFF, dmainfo[channel].length);

  // Unmask
  outb(channel, 0x0A);

 // Enabling IRQs
  outb(0, 0x21);
  outb(0, 0xA1);


I use it to transfer a sector from the floppy disk. Do you see anything
wrong in this code ?
The transfer is not made by the floppy, and i don't know why...
I don't know if it's in the DMA programming, or in the floppy driver

Help !


Thomas, from france

(If you speak french, you can join the KOS project :

PETAZZONI Thomas, coordinateur du projet KOS 
thomas.petazzoni at ifrance.com
ICQ : 34937744
Home page : http://perso.worldonline.fr/petazzoni/thomas/
Home Page Projet KOS : http://kos.enix.org

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