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

[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 <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 something broken here, 
that this patch doesn't fix either.


Alex