[OpenBIOS] L2 Cache Settings

Segher Boessenkool segher at kernel.crashing.org
Tue Jan 23 22:57:26 CET 2018


On Mon, Jan 22, 2018 at 10:35:17PM -0500, Programmingkid wrote:
> > On Jan 22, 2018, at 9:50 PM, James Lyons via OpenBIOS <openbios at openbios.org> wrote:
> > 
> > Looks like for the 7447a we set SPR 1017( L2CR ) bit 0 ( L2E ) or just write 0x8000000 to the reg.
> > 
> > Not sure how we do this in Openbios.
> 
> This would be done in PowerPC assembly. A C function can contain the inline assembly code. 
> 
> It would look something like this:
> 
> void setup_PPC_7447a(void)
> {
>     asm volatile("addis r10, 0, 0x8000");
>     asm volatile("mtspr 1017, r10");
> }

That is incorrect asm.  You cannot use r10, it can already be in use,
and you cannot pass a reg between two separate asm statements like this.

You meant something like

void enable_L2_7447A(void)
{
	asm("mtspr %0,%1" : : "n"(1017), "r"(0x80000000));
}

(but see my other mail, this is not enough to enable L2).


Segher



More information about the OpenBIOS mailing list