Date: Wed, 27 Jan 1999 13:32:25 +0100 (MET) From: Joerg Czeranski <jc@joerch.org> To: shimon@simon-shapiro.org Cc: freebsd-alpha@FreeBSD.ORG Subject: Re: Alpha Driver Help Requested Message-ID: <199901271232.NAA23834@zaphod.in.tu-clausthal.de> In-Reply-To: <XFMail.990126052812.shimon@simon-shapiro.org>
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Simon Shapiro wrote:
> * The driver panics on trap entry 0x4 (unaligned access fault). This
> happens in the following code snippet:
>
> dpt_outl(dpt, HA_WDMAADDR, cmd_busaddr);
>
> All the arguments are of the correct type.
And:
> I narrowed down the failure to line 467 in sys/alpha/bus.h which simply
> says:
>
> outl(bsh + offset, value);
And:
> fatal kernel trap:
>
> trap entry = 0x4 (unaligned access fault)
> a0 = 0xfffffca900010192
> a1 = 0x2c
> a2 = 0x11
> pc = 0xfffffc00004a77bc
> ra = 0xfffffc000034f958
> curproc = 0
Decoding the values:
/usr/src/sys/dev/dpt/dpt.h: #define HA_WDMAADDR 0x02
alpha/pci/ciareg.h: #define CIA_EV56_BWIO 0x8900000000UL
The base address of the DPT probably is 0x10190.
Thus a0 is a bus space address (for use with the Byte/Word/eXtension of
>= EV56 implementations) aligned to a word (16bit), but it is used by
outl for a longword (32bit) access. This results in the unaligned
access fault.
Either a 32 bit access wasn't intended (it overlaps with HW_WCODE and
HW_WCODE2 anyway, maybe a bug?) or it must be split into two 16 bit
writes.
joerch
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