[LinuxBIOS] Intel 440bx

[Sven Rebhan]

Corey Osgood wrote:
> So, I commented all the do_ram_commands out (since I can't see
> the problem with it) and did ram init using pci_write_config16, setting
> what I know the values should be, and then NOP would not report as being
> set (and ram still failed). So, I set up a for loop to set NOP until the
> northbridge reported that it was set...I got an infinite loop. My loop
> might be wrong (it's a bit hackish), can someone tell me if it should
> work? Or does NOP simply not set?
>
> /* 3. Apply NOP. */
> RAM_DEBUG_MESSAGE("Ram Enable 3: Apply NOP\r\n");
> int s;
> for( s = 0; s != 0110; s = pci_read_config16( ctrl->d0, SDRAMC )  ) {
> 	RAM_DEBUG_MESSAGE("Do NOPs til it cooperates!\r\n");
> 	pci_write_config8(ctrl->d0, SDRAMC, 0x0110);
> 	read32(0x04000000);
> 	EXTRA_DELAY
> }

Hello everybody,

I am new to LinuxBios and interested in getting an Asus P2B-F (i440bx)
up and running. Therefor I read the Intel specifications and regarding
to the code above the following paragraph got my attention (section
3-1, p. 27):

  Some of the 82443BX registers described in this section contain reserved bits.
  These bits are labeled "Reserved". Software must deal correctly with
fields that are
  reserved. On reads, software must use appropriate masks to extract the defined
  bits and not rely on reserved bits being any particular value. On
writes, software
  must ensure that the values of reserved bit positions are preserved.
That is, the
  values of reserved bit positions must first be read, merged with the
new values for
  other bit positions and then written back.

If I understood this correctly we have to do

  /* 3. Apply NOP. */
  RAM_DEBUG_MESSAGE("Ram Enable 3: Apply NOP\r\n");
  int s;
  for( s = 0; s  != 0x0110 & 0x03ff; s = pci_read_config16( ctrl->d0,
SDRAMC )  ) {
        RAM_DEBUG_MESSAGE("Do NOPs til it cooperates!\r\n");
        pci_write_config8(ctrl->d0, SDRAMC, 0x0110 | (s & 0xfc00));
        read32(0x04000000);
        EXTRA_DELAY
  }

Unfortunately I can't test this myself, because my test-setup is still
not complete...