Re: [SeaBIOS] your mail

[Kevin O'Connor]

On Mon, Feb 08, 2010 at 11:41:59AM +0100, [e-mail] wrote:
> Hello,
> I'm trying to read the timer in Seabios to test elapsed time between functions.
> Here is my code:
> static void readtimer(void)
> {
>     // Read timer
>     struct bregs br;
>     memset(&br, 0, sizeof(br));
>     br.flags = F_IF;
>     br.ah = 0x00;
> call16_int(0x1a, &br);
>
> dprintf(1, "timer:%d %d %d\n",br.cx,br.dx,br.al);
>
> }
>
> But gcc tells:
> undefined reference to `irq_trampoline_0x1a' (or 26 dec)

In order to use call16_int() an assembler "trampoline" needs to be
defined.  Just add "IRQ_TRAMPOLINE 1a" to the src/romlayout.S file
next to the other trampolines.

BTW, the rdtscll() function and cpu_khz variable may be a more direct
way of measuring times in SeaBIOS.

-Kevin