Re: [PATCH v3] aspeed: Add boot stub for smp booting

[Cédric Le Goater]

On 5/8/20 8:52 AM, Joel Stanley wrote:
> On Mon, 4 May 2020 at 08:20, Joel Stanley <address@hidden> wrote:
> ...
> 
>> v3: Use WFI instead of WFE
>> v2: test for number of CPUs
> 
>> +static void aspeed_write_smpboot(ARMCPU *cpu,
>> +                                 const struct arm_boot_info *info)
>> +{
>> +    static const uint32_t poll_mailbox_ready[] = {
>> +        /*
>> +         * r2 = per-cpu go sign value
>> +         * r1 = AST_SMP_MBOX_FIELD_ENTRY
>> +         * r0 = AST_SMP_MBOX_FIELD_GOSIGN
>> +         */
>> +        0xee100fb0,  /* mrc     p15, 0, r0, c0, c0, 5 */
>> +        0xe21000ff,  /* ands    r0, r0, #255          */
>> +        0xe59f201c,  /* ldr     r2, [pc, #28]         */
>> +        0xe1822000,  /* orr     r2, r2, r0            */
>> +
>> +        0xe59f1018,  /* ldr     r1, [pc, #24]         */
>> +        0xe59f0018,  /* ldr     r0, [pc, #24]         */
>> +
>> +        0xe320f003,  /* wfi                           */
> 
> I was wrong, wfi does not work in this case. I must have made a
> mistake when testing.
> 
> Cédric, can you please confirm my testing is correct? I was using
> today's linux next, but anything newer than Linux 5.4 should have the
> same result.

Indeed, with OpenBMC kernel v5.4.32-260-g7dc9442bbe7d and wfi (patch v3), 
    
    [    0.045214] smp: Bringing up secondary CPUs ...
    [    1.178127] CPU1: failed to come online
    [    1.187309] smp: Brought up 1 node, 1 CPU
    [    1.187590] SMP: Total of 1 processors activated (2250.00 BogoMIPS).
    [    1.187786] CPU: All CPU(s) started in HYP mode.
    [    1.187850] CPU: Virtualization extensions available.

When using wfe (patch v2),

    [    0.091092] smp: Bringing up secondary CPUs ...
    [    0.096628] smp: Brought up 1 node, 2 CPUs
    [    0.096718] SMP: Total of 2 processors activated (4500.00 BogoMIPS).
    [    0.096768] CPU: All CPU(s) started in HYP mode.
    [    0.096785] CPU: Virtualization extensions available.


Cheers,

C.