[SeaBIOS] [PATCH 3/3] Take in account hot(un)plugged cpus on reboot

[Igor Mammedov]

On 03/13/2012 01:09 AM, Kevin O'Connor wrote:
> On Sat, Mar 10, 2012 at 12:47:28PM +0100, Igor Mammedov wrote:
>> Initial count of active cpus is communicated to bios from qemu via
>> CMOS_BIOS_SMP_COUNT io port. However if cpus are hotplugged after
>> boot and then guest is rebooted without taking down qemu then
>> bios might be stuck at smp_probe
> [...]
>> --- a/src/smp.c
>> +++ b/src/smp.c
>> @@ -17,6 +17,9 @@
>>
>>   #define APIC_ENABLED 0x0100
>>
>> +#define ACPI_CPU_STATUS_MAP 0xaf00
>> +#define ACPI_CPU_STATUS_MAP_SZ 32
>> +
>>   struct { u32 ecx, eax, edx; } smp_mtrr[32] VAR16VISIBLE;
>>   u32 smp_mtrr_count VAR16VISIBLE;
>>
>> @@ -115,6 +118,26 @@ smp_probe(void)
>>           msleep(10);
>>       } else {
>>           u8 cmos_smp_count = inb_cmos(CMOS_BIOS_SMP_COUNT);
>> +        dprintf(1, "Powered-on with %d cpu(s)\n", cmos_smp_count + 1);
>> +
>> +        if (qemu_cfg_have_acpi_cpus_map()) {
> [...]
>
> Please don't clutter up smp.c with this.  The code should look
> something like:
>
>            int total_cpus = getCPUcount();
>            while (readl(&CountCPUs)<  total_cpus)
>                yield();
>
> The getCPUcount() can be buried in paravirt.c, acpi.c, or where ever
> it makes sense.

Thanks Kevin,
I'll amend and repost patch-set taking in account your suggestions.

> BTW, why do we have to call qemu_cfg_have_acpi_cpus_map?  Can't this
> just be inferred if the data at inb(0xaf00) is all zeros?
What if qemu doesn't have 0xaf00 (like current upstream)?
cfg_have_acpi_cpus_map is just a flag that allows to detect if qemu
provides 0xaf00. This way it would be possible for seabios to work with
old and new versions of qemu without breaking anything.

>
> -Kevin

-- 
-----
  Igor