Re: [Qemu-ppc] [PATCH] ppc: initialize GPRs as per epapr

[Alexander Graf]

On 26.04.2013, at 08:51, Bhushan Bharat-R65777 wrote:

> 
> 
>> -----Original Message-----
>> From: Alexander Graf [mailto:address@hidden
>> Sent: Friday, April 26, 2013 11:51 AM
>> To: Bhushan Bharat-R65777
>> Cc: address@hidden; address@hidden; Wood Scott-B07421; Bhushan
>> Bharat-R65777; Yoder Stuart-B08248
>> Subject: Re: [PATCH] ppc: initialize GPRs as per epapr
>> 
>> 
>> On 26.04.2013, at 08:17, Bharat Bhushan wrote:
>> 
>>> ePAPR defines the initial values of cpu registers. This patch
>>> initialize the GPRs as per ePAPR specification.
>>> 
>>> This resolves the issue of guest reboot/reset (guest hang on reboot).
>> 
>> Why does it hang only on reboot, not on initial bootup?
> 
> may be memory pointed by env pointer are zero initialized initially.
> Reboot also not always hangs. I have seen reboot mostly working on 
> e500v2/e500mc and mostly hanging on e5500.

Yes, they're all zero initialized. I'm surprised that got things working.

> 
>> 
>>> 
>>> Signed-off-by: Bharat Bhushan <address@hidden>
>>> Signed-off-by: Stuart Yoder <address@hidden>
>>> ---
>>> hw/ppc/e500.c |    7 +++++++
>>> 1 files changed, 7 insertions(+), 0 deletions(-)
>>> 
>>> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c index c1bdb6b..a47f976
>>> 100644
>>> --- a/hw/ppc/e500.c
>>> +++ b/hw/ppc/e500.c
>>> @@ -37,6 +37,7 @@
>>> #include "qemu/host-utils.h"
>>> #include "hw/pci-host/ppce500.h"
>>> 
>>> +#define EPAPR_MAGIC                (0x45504150)
>>> #define BINARY_DEVICE_TREE_FILE    "mpc8544ds.dtb"
>>> #define UIMAGE_LOAD_BASE           0
>>> #define DTC_LOAD_PAD               0x1800000
>>> @@ -444,6 +445,12 @@ static void ppce500_cpu_reset(void *opaque)
>> 
>> Does ePAPR mention anything wrt GPR state of secondary CPUs?
> 
> Yes, I think we handle this in hw/ppc/ppce500_spin.c
> 
>> 
>>>    cs->halted = 0;
>>>    env->gpr[1] = (16<<20) - 8;
>>>    env->gpr[3] = bi->dt_base;
>>> +    env->gpr[4] = 0;
>>> +    env->gpr[5] = 0;
>>> +    env->gpr[6] = EPAPR_MAGIC;
>>> +    env->gpr[7] = (64 * 1024 * 1024);
>> 
>> What is this?
> 
> Size of initial TLB ( should be big enough to cover kernel handler). I do not 
> see ePAPR defines any value, I set this to 64M.

It's dynamic. Please set it to the actual size of the initial TLB mapping we 
create.


Alex