On 01/04/2017 01:19 PM, Andrew Lunn wrote:
> On Wed, Jan 04, 2017 at 04:11:03PM -0500, David Miller wrote:
>> From: Andrew Lunn <and...@lunn.ch>
>> Date: Wed, 4 Jan 2017 19:56:24 +0100
>>
>>> +static inline u64 ether_addr_to_u64(const u8 *addr)
>>> +{
>>> + u64 u = 0;
>>> + int i;
>>> +
>>> + for (i = 0; i < ETH_ALEN; i++)
>>> + u = u << 8 | addr[i];
>>> +
>>> + return u;
>>> +}
>> ...
>>> +static inline void u64_to_ether_addr(u64 u, u8 *addr)
>>> +{
>>> + int i;
>>> +
>>> + for (i = ETH_ALEN - 1; i >= 0; i--) {
>>> + addr[i] = u & 0xff;
>>> + u = u >> 8;
>>> + }
>>> +}
>>
>> I think these two routines behave differently on big vs little
>> endian. And I doubt this was your intention.
>
> I don't have a big endian system to test on.
You could build the driver for e.g: a MIPS Malta board and use the
qemu-system-mips to validate this, there could be a way to do that on
ARM too although it's a different kind of BE (BE8 vs. BE32) AFAIR.
>
> I tried to avoid the usual pitfalls. I don't cast a collection of
> bytes to a u64, which i know has no chance of working. Accessing a MAC
> address as a byte array should be endian safe. The shift operation
> should also be endian safe.
>
> What exactly do you think will behave differently?
>
> Andrew
>
--
Florian
