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

[Alexander Graf]

On 01.05.2013, at 01:54, Chen, Tiejun wrote:

>> -----Original Message-----
>> From: Alexander Graf [mailto:address@hidden 
>> Sent: Tuesday, April 30, 2013 5:53 PM
>> To: Scott Wood
>> Cc: Chen, Tiejun; address@hidden; address@hidden
>> Subject: Re: [Qemu-ppc] [v1][PATCH 1/1] PPC: e500: correct 
>> params->ram_size with ram_size
>> 
>> 
>> 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 <address@hidden>
>>>> ---
>>>> 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.
>> 
>> What bug are you trying to fix? Maybe there really is 
> 
> I had an explanation when I reply to Scott, could you take a look at that?

I think it makes sense.

> If you have no further objection, I'd like to send next version with 
> withdrawing that comment as Scott suggest.

Yes, please :)


Alex