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Date: Thu, 30 Sep 2010 10:07:43 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH] lsi53c895a: Add missing registers and
 workaround for OS/2 Warp SYM8XX.ADD driver
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To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, kvm-devel <kvm@vger.kernel.org>, Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel <qemu-devel@nongnu.org>, FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>, Hannes Reinecke <hare@suse.de>, Matthew Wilcox <willy@linux.intel.com>, Paul Brook <paul@codesourcery.com>

On 09/30/2010 07:07 AM, Nicholas A. Bellinger wrote:
>       case 0x06: /* SDID */
> -        if ((val&  0xf) != (s->ssid&  0xf))
> -            BADF("Destination ID does not match SSID\n");
> +        /*
> +         * This workaround is required by the SYM8XX.ADD driver for OS/2 Warp.
> +         */
> +        if ((val&  0xf) != (s->ssid&  0xf)) {
> +            DPRINTF("Destination ID does not match SSID, val: %02x"
> +                    " s->ssid: %02x, fixing up val\n", val, s->ssid);
> +            val = s->ssid;
> +        }
>           s->sdid = val&  0xf;
>           break;

I don't think the write is bogus, as the manual says "Writing these bits 
set the SCSI ID of the intended initiator or target during SCSI 
reselection or selection phases, respectively".

The value is never used by the device model, only read/written according 
to SCRIPTS and register read/writes.  How does the OS/2 driver use it? 
Have you tried, just removing the "if" without replacing it?

Paolo