Dual Core Programming: CPU1 starts automatically e...

kilasue · ‎08-02-2020

CPU1:

Xil_SetTlbAttributes(0xFFFF0000,0x14de2);
cout<<"CPU1: Initialized."<<endl;
wfe();
cout<<"CPU1: After WFE."<<endl;

CPU0:

Xil_SetTlbAttributes(0xFFFF0000,0x14de2);
cout<<"CPU0: writing start address for CPU1."<<endl;
sleep(5);
Xil_Out32(CPU1STARTADR, CPU1STARTMEM);
dmb(); //waits until write has finished
sev();

I expect after 5 seconds of CPU0's output, there will be CPU1's output. But actually, every time I run debug configuration, 3 cout strings of CPU0 and CPU1 appear instantly.

So I think that CPU1 is started automatically, how can I actually let CPU0 starts CPU1? What's more, wfe() instruction on CPU1 apparently has no effect.

Notes:

1. I have add -DUSE_AMP=1 flags in CPU1's board support package.

Now by stepping instructions on CPU1 one by one:

#elif XPAR_CPU_ID==1
	/* only allow cpu1 through */
       mrc	p15,0,r1,c0,c0,5
       and	r1, r1, #0xf
       cmp	r1, #1
       beq	CheckEFUSE1
       b        EndlessLoop1

CheckEFUSE1:
        ldr r0,=EFUSEStaus
        ldr r1,[r0]                             /* Read eFuse setting */
        ands r1,r1,#0x80                        /* Check whether device is having single core */
	beq OKToRun
	EndlessLoop1:
	        wfe
	b	EndlessLoop1
#endif
OKToRun:

I find that after CPU1 executing beq OKToRun, it goes to region OKToRun. It looks like CPU1 fails to recognize that it's in a multi-core system.

Dual Core Programming: CPU1 starts automatically even without CPU0's SEV intruction.