Re: [PATCH 1/2] docs, xen/arm: Introduce reserved heap memory

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Henry,

On 30/08/2022 02:58, Henry Wang wrote:
> 
> Hi Stefano and Michal,
> 
>> -----Original Message-----
>> From: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> Sent: Tuesday, August 30, 2022 8:47 AM
>> To: Henry Wang <Henry.Wang@xxxxxxx>
>> Cc: Michal Orzel <michal.orzel@xxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx;
>> Stefano Stabellini <sstabellini@xxxxxxxxxx>; Julien Grall <julien@xxxxxxx>;
>> Bertrand Marquis <Bertrand.Marquis@xxxxxxx>; Wei Chen
>> <Wei.Chen@xxxxxxx>; Volodymyr Babchuk
>> <Volodymyr_Babchuk@xxxxxxxx>; Penny Zheng <Penny.Zheng@xxxxxxx>
>> Subject: RE: [PATCH 1/2] docs, xen/arm: Introduce reserved heap memory
>>
>> On Thu, 25 Aug 2022, Henry Wang wrote:
>>>>>                                         const char *name,
>>>>>                                         u32 address_cells, u32 size_cells)
>>>>>  {
>>>>> @@ -301,16 +303,40 @@ static void __init process_chosen_node(const
>>>> void *fdt, int node,
>>>>>      paddr_t start, end;
>>>>>      int len;
>>>>>
>>>>> +    if ( fdt_get_property(fdt, node, "xen,static-mem", NULL) )
>>>>> +    {
>>>>> +        u32 address_cells = device_tree_get_u32(fdt, node,
>>>>> +                                                
>>>>> "#xen,static-mem-address-cells",
>>>>> +                                                0);
>>>>> +        u32 size_cells = device_tree_get_u32(fdt, node,
>>>>> +                                             
>>>>> "#xen,static-mem-size-cells", 0);
>>>>> +        int rc;
>>>>> +
>>>>> +        printk("Checking for reserved heap in /chosen\n");
>>>>> +        if ( address_cells < 1 || size_cells < 1 )
>>>> address_cells and size_cells cannot be negative so you could just check if
>>>> there are 0.
>>>
>>> In bootfdt.c function device_tree_get_meminfo(), the address and size cells
>>> are checked using <1 instead of =0. I agree they cannot be negative, but I
>> am
>>> not very sure if there were other reasons to do the "<1" check in
>>> device_tree_get_meminfo(). Are you fine with we don't keep the
>> consistency
>>> here?
>>
>> I would keep the < 1 check but it doesn't make much difference either
>> way
> 
> I also would prefer to keep these two places consistent and I agree Michal is
> making a good point.
I'm ok with that so let's keep the consistency.

> 
> Kind regards,
> Henry
> 

~Michal