Re: ibmvtpm byteswapping inconsistency

From: Michael Ellerman
Date: Tue Jan 31 2017 - 03:38:43 EST


Tyrel Datwyler <tyreld@xxxxxxxxxxxxxxxxxx> writes:
> On 01/29/2017 08:32 PM, Michael Ellerman wrote:
>> Tyrel Datwyler <tyreld@xxxxxxxxxxxxxxxxxx> writes:
>>>
>>> Byte | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
>>> -----------------------------------------------------------------------
>>> Word0 | Valid | Type | Length | Data
>>> -----------------------------------------------------------------------
>>> Word1 | Reserved
>>> -----------------------------------------------------------------------
>>>
>>> The following definition looks to match:
>>>
>>> struct ibmvtpm_crq {
>>> u8 valid;
>>> u8 msg;
>>> __be16 len;
>>> __be32 data;
>>> __be64 reserved;
>>> } __attribute__((packed, aligned(8)));
>>
>> Well it's a partial match.
>>
>> Your layout above doesn't define which byte of Length or Data is the MSB
>> or LSB. So going by that we still don't know the endianness of either
>
> I should have been explicit that PAPR uses Big Endian bit and byte
> numbering throughout the spec unless otherwise noted.

OK. I didn't actually remember that so yeah good to be explicit.

cheers