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Date:      21 Apr 1998 07:17:27 GMT
From:      peter@netplex.com.au (Peter Wemm)
To:        freebsd-scsi@FreeBSD.ORG
Subject:   Re: ahh, I think I see part of the problem.. (CAM bouncing)
Message-ID:  <6hhh67$7m7$2@haywire.dialix.com.au>
References:  <199804201933.DAA08958@spinner.netplex.com.au>

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In article <199804210624.AAA03372@pluto.plutotech.com>,
	gibbs@plutotech.com (Justin T. Gibbs) writes:
>>I tried the previous patch that you posted but had a pretty spectacular 
>>explosion on a BT545S..  It "found" devices all the way up to da11 (at 
>>target 2 lun 5) and failed to mount root.  The probes were reporting 
>>garbage..  Hmm..  Are all the allocations being zeroed?
> 
> I don't think that is the problem.  It is more likely caused by using
> the wrong dmat on line 261 of bt_isa.c:
> 
>                 if (bus_dmamem_alloc(bt->sense_dmat, <= Used to be mailbox_dmat
> 
> This would allocate the incorrect amount of sense bounce space causing 
> untold trouble.

I'll say.. :-)
 
>>I added a 'if (addr == 0) return (1)' type test at the end of the vlfilter 
>>function, but the 445S doesn't work properly either.  Things get SEGV 
>>during bootup to multi-user (eg: sendmail, nmbd etc), and the system 
>>usually panics with a 'vm_fault on nofault entry' type panic fairly 
>>shortly after that.  I suspect the bios shadow avoidance has kicked in and 
>>a bug has been triggered (it doesn't work on the 545S at all, so that's 
>>why I suspect the bouncing).
> 
> It is probably the sense buffering bug again, but it is only triggered 
> after more commands are run as the VL card has more CCBs than the ISA
> card and the size of the mailbox_dmat is based on number of CCBs.
> 
> I hate writing code blind.  I'd rather catch my coding bugs myself than
> have others suffer through it. 8-)

That's what testers are for..  Although I'm quietly thankful that it hasn't
scrambled block read commands to make them look like scsi 'format disk'
commands... :-)

Cheers,
-Peter

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