Re: [Qemu-devel] [Qemu-ppc] [v1][PATCH 1/1] PPC: e500: correct params->ram_size with ram_size

["Andreas Färber" <afaerber@suse.de>]

Am 30.04.2013 11:53, schrieb Alexander Graf:
> 
> On 29.04.2013, at 21:18, Scott Wood wrote:
> 
>> On 04/28/2013 05:30:09 AM, Tiejun Chen wrote:
>>> We should sync params->ram_size after we fixup memory size on
>>> a alignment boundary. Otherwise Guest would exceed the actual
>>> memory region.
>>> Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
>>> ---
>>> hw/ppc/e500.c |    2 ++
>>> 1 file changed, 2 insertions(+)
>>> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
>>> index c1bdb6b..145da0e 100644
>>> --- a/hw/ppc/e500.c
>>> +++ b/hw/ppc/e500.c
>>> @@ -523,6 +523,8 @@ void ppce500_init(PPCE500Params *params)
>>>     /* Fixup Memory size on a alignment boundary */
>>>     ram_size &= ~(RAM_SIZES_ALIGN - 1);
>>> +    /* Sync this for the system. */
>>> +    params->ram_size = ram_size;
>>
>> Could you explain this further?  When does params->ram_size ever get used after this point?
> 
> This is the respective code in vl.c:
> 
>>     QEMUMachineInitArgs args = { .ram_size = ram_size,
>>                                  .boot_device = (boot_devices[0] == '\0') ?
>>                                                 machine->boot_order :
>>                                                 boot_devices,
>>                                  .kernel_filename = kernel_filename,
>>                                  .kernel_cmdline = kernel_cmdline,
>>                                  .initrd_filename = initrd_filename,
>>                                  .cpu_model = cpu_model };
>>     machine->init(&args);
> 
> 
> After this, args in unused. So as you can see, params->ram_size never gets used after it's read once.

While that is true, it was being discussed to update cpu_model inside
QEMUMachineInitArgs FWIW. That's independent of PPCE500Params though.

Andreas

> What bug are you trying to fix? Maybe there really is something broken here, that this patch doesn't fix either.
> 
> 
> Alex

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