From: Chris Cappuccio <chris@nmedia.net>
Subject: Re: uncm(4): process all notifications in one interrupt transfer
To: Mikolaj Kucharski <mikolaj@kucharski.name>, tech@openbsd.org, Jan Schreiber <jes@posteo.de>
Date: Mon, 12 Oct 2026 06:55:55 -0700

Stefan Sperling [stsp@stsp.name] wrote:
> 
> Could we copy these messages out of sc_intr_msg into another variable
> of struct usb_cdc_notification type with memcpy() after checking sizes?
> 
> We must avoid unaligned access on some platforms OpenBSD supports. Just
> casting a uint8_t * type to a struct * type could make us end up in ddb
> on such platforms if the device doesn't align its messages as expected
> by the platform.
> 
> I realize this makes the driver slower and we're already copying data from
> and to USB transfers. But complicated message framing like this has a cost.
> 

there's always __STRICT_ALIGNMENT so network drivers can choose an
optimal path

#ifdef __STRICT_ALIGNMENT
 copies
#else
 maybe less copies
#endif