[coreboot] alix1c and v3
tsylla at gmail.com
Tue Jan 29 08:17:58 CET 2008
ron minnich wrote:
> here's an interesting bug in
> /* Dump zeros in the other segment registers */
> " mov %ax, %es \n"
> " mov %ax, %fs \n"
> " mov %ax, %gs \n"
> " mov $0x40, %ax \n"<----------------------WHAT?
> " mov %ax, %ds \n"
> " mov %cx, %ax \n"
> Why did somebody move 0x40 to the ds? That's not even a valid gdt selector?
> Anybody know why this was done?
That is probably normal. These are real mode selectors (segment
registers), and that code is calling a VGA ROM. 0x40:xx is the BDA. I
think that is one of the expectations of a VGA ROM is that it is called
with the BDA pointed to be ds. cx has the device/function of the card
Your generic case won't want that stuff (and it doesn't have it now)
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