Date: Mon, 20 Apr 1998 22:42:17 GMT From: jak@cetlink.net (John Kelly) To: "Justin T. Gibbs" <gibbs@plutotech.com> Cc: scsi@FreeBSD.ORG Subject: Re: ahh, I think I see part of the problem.. (CAM bouncing) Message-ID: <353cce7e.94813933@mail.cetlink.net> In-Reply-To: <199804201657.KAA28393@pluto.plutotech.com> References: <199804201657.KAA28393@pluto.plutotech.com>
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On Mon, 20 Apr 1998 10:53:12 -0600, "Justin T. Gibbs" <gibbs@plutotech.com> wrote: >>It seems that bus_dmamem_alloc() is flawed if a filter function is active, >>for starters. With a Bt-445S, it's got to bounce the 'paddr % 16MB == >>biosaddr' pages, so the contigmalloc() will allocate pages from the entire >>memory pool (since the 445S has a 32bit dma limit), and yet bouncing may >>still need to happen. Incidently, what happens if contigmalloc() >>allocates a page from the shadow of the bios rom addr? :-) > >Take a good look at the initialization code in bt_isa.c. If we have to >install a filter, we set the address range for the filter to be 16MB->4GB. >bus_dmamem_alloc and the code that allocates bounce pages only allocates >space below the low address specified in the dma tag. This should ensure >that we allocate pages that can replace any page rejected by the filter. >So, the setup for a broken 445S is the same as an ISA card except that we >include a filter that will allow 99% of the pages above 16MB. After reading this I don't understand what's broken about the 445S. Could you put it in more simple language? I have some 445C adapters and I wonder if they have the same characteristic. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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