[rt2x00-users] padding and alignment

Benoit PAPILLAULT benoit.papillault at free.fr
Fri Aug 14 13:34:53 UTC 2009

Ivo Van Doorn a écrit :
> For some chipsets it means the frame will not be send out, I am not
> aware of a performance hit.

OK, i will do test this way. I will try every kind of addresses for
SDPTR0 and SDPTR1 (be it a multiple of 4 + 0, 1, 2, 3).

> Well HW crypto is broken in rt2800pci, so you should always test it
> with software crypto. And even when it is working, all drivers should work
> with software encryption since it is important for testing purposes or when
> frames should be encrypted which the hardware can't encrypt itself (due to
> new ieee80211 specifications).

Hummm... Using SW crypto use way too much CPU, but i know that some
cases are not handled by the HW, so I think we use either use SW crypto
for testing purpose and a mix of HW/SW crypto for real world and 802.11

The good news is that rt2800pci is properly working in WPA2 STA mode
(I'm using it on a 2.6.30-wl based kernel since 2.6.31-rc5-wl was not
working at all).

> But my point is, that there are different code paths depending on HW
> or SW crypto,
> and both should make sure the frame is properly aligned.
>> BTW, does the same alignment requirements apply to rt2800usb (i just
>> got 2 hardware based on rt2870)?
> Yes. The chipsets are practically identical and the main difference is
> the USB vs PCI thing.


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