Re: kern/50038: udl (DisplayLink GX-DVI_U2B) alignment fault on earmv6hf NETWALKER

[Nick Hudson <skrll%netbsd.org@localhost>]

On 11/14/16 20:30, MOCHIDA Shuji wrote:
> The following reply was made to PR kern/50038; it has been noted by GNATS.
>
> From: MOCHIDA Shuji <mochid%netside.co.jp@localhost>
> To: martin%duskware.de@localhost
> Cc: skrll%netbsd.org@localhost, gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost,
>   gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, mochid%netside.co.jp@localhost
> Subject: Re: kern/50038: udl (DisplayLink GX-DVI_U2B) alignment fault on
>   earmv6hf NETWALKER
> Date: Tue, 15 Nov 2016 03:31:56 +0900 (JST)
>
>   Easy workaround below. May something related to alignment.
>   In these functions, (curcpu()->ci_ctrl & CPU_CONTROL_AFLT_ENABLE) is zero.
>   This should not be zero?
>   

We should be running with SCTLR.A =0 and SCTLR.U = 1, i.e.
CPU_CONTROL_AFLT_ENABLE unset and CPU_CONTROL_UNAL_ENABLE set, but
I think the usb transfer buffer is being marked as device/strongly 
ordered memory and
we get an unaligned access fault because of this.

Nick