Re: [PATCH] pnv/ppc: Set default RAM size to 1 GB

[Cédric Le Goater]

On 1/29/21 11:11 AM, Greg Kurz wrote:
> On Fri, 29 Jan 2021 10:39:12 +0100
> Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
> 
>> On 1/29/21 10:29 AM, Cédric Le Goater wrote:
>>> Any value below will result in a skiboot crash :
>>>
>>>     [    0.034949905,3] MEM: Partial overlap detected between regions:
>>>     [    0.034959039,3] MEM: ibm,firmware-stacks [0x31c10000-0x3a450000] 
>>> (new)
>>>     [    0.034968576,3] MEM: ibm,firmware-allocs-memory@0 
>>> [0x31c10000-0x38400000]
>>>     [    0.034980367,3] Out of memory adding skiboot reserved areas
>>>     [    0.035074945,3] ***********************************************
>>>     [    0.035093627,3] < assert failed at core/mem_region.c:1129 >
>>>     [    0.035104247,3]     .
>>>     [    0.035108025,3]      .
>>>     [    0.035111651,3]       .
>>>     [    0.035115231,3]         OO__)
>>>     [    0.035119198,3]        <"__/
>>>     [    0.035122980,3]         ^ ^
>>>
>>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>>> ---
>>>  hw/ppc/pnv.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
>>> index 50810df83815..70ce12f6dc73 100644
>>> --- a/hw/ppc/pnv.c
>>> +++ b/hw/ppc/pnv.c
>>> @@ -1994,7 +1994,7 @@ static void pnv_machine_class_init(ObjectClass *oc, 
>>> void *data)
>>>       * RAM defaults to less than 2048 for 32-bit hosts, and large
>>>       * enough to fit the maximum initrd size at it's load address
>>>       */
>>> -    mc->default_ram_size = INITRD_LOAD_ADDR + INITRD_MAX_SIZE;
>>> +    mc->default_ram_size = 1 * GiB;
>>
>> Maybe also just in case add before the definitions:
>>
>>   QEMU_BUILD_BUG_ON(INITRD_LOAD_ADDR + INITRD_MAX_SIZE > 1 * GiB);
>>
> 
> or
> 
>     mc->default_ram_size = MAX(1 * GiB, INITRD_LOAD_ADDR + INITRD_MAX_SIZE)


The memory layout of the PowerNV machine is defined as :

  #define KERNEL_LOAD_BASE      ((void *)0x20000000)
  #define KERNEL_LOAD_SIZE      0x08000000

  #define INITRAMFS_LOAD_BASE   KERNEL_LOAD_BASE + KERNEL_LOAD_SIZE
  #define INITRAMFS_LOAD_SIZE   0x08000000

  #define SKIBOOT_BASE          0x30000000

  /* bunch of areas: head, console buffers, TCEs, etc  */
  #define SKIBOOT_SIZE          0x01c10000
  #define CPU_STACKS_BASE       (SKIBOOT_BASE + SKIBOOT_SIZE)

  #define STACK_SHIFT           15
  #define STACK_SIZE            (1 << STACK_SHIFT)

The overall size of the CPU stacks is (max PIR + 1) * 32K and the 
machine easily reaches 800MB of minimum required RAM.

I don't remember where INITRD_LOAD_ADDR + INITRD_MAX_SIZE came from
but it is a bit bogus.

For now, I will send a v2 with a stronger check similar to what other 
machines do. May be we should consider adding a 'min_ram_size' in
MachineClass. 

Thanks,

C.