Date: Thu, 22 Jun 2000 15:54:40 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: =?ISO-8859-1?Q?G=E9rard_Roudier?= <groudier@club-internet.fr> Cc: freebsd-alpha@FreeBSD.ORG Subject: Re: Problems installing FreeBSD 4.0-RELEASE on an Alpha system Message-ID: <14674.26845.214876.230507@grasshopper.cs.duke.edu> In-Reply-To: <Pine.LNX.4.10.10006222031520.1257-100000@linux.local> References: <14674.13167.247088.580096@grasshopper.cs.duke.edu> <Pine.LNX.4.10.10006222031520.1257-100000@linux.local>
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Gérard Roudier writes: > 3) The BUS physical addresses (as seen from PCI BUS), the SCRIPTS > processor is provided with, are wrong. > > Given that the driver succeeded initialisations and seems to successfully > read chip IO registers using MMIO, the actual reason of the breakage is > probably not (1) and (2) does not seem to me a good culprit :). > > Regarding possible reason (3), the SCRIPTS processor fetches instructions > from on-chip RAM using internal path (not using PCI external cycles). > For this to work, the BAR that is supposed to contain the address of > the on-chip RAM must match the BUS physical address of the on-chip RAM > as seen from the BUS. > > If for some reason BUS physical addresses ad seen from CPU differs from > BUS physical address as seen from the PCI BUS, and the BAR contains the > former address value, then the current driver code will not work. A > work-around could consist in using main memory for SCRIPTS instead of > on-chip RAM. #3 is most likely the culprit. Right now we steal the upper bit(s) of the port or address passed down to the chipset's inX/outX readX/writeX functions to allow drivers to use inX/outX and readX/writeX. This is done so as to give hints to the lowlevel chipset code as to which hose the address in question is on. This hackery will go away when the previously mentioned changes to the alpha pci code happen. (Those changes are why Doug wanted to get all important drivers using busspace). Thanks for explaining it! I've long suspected that something like this was going on but never had the time to really understand either ncr driver well enough to figure it out for myself. Cheers, Drew To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the messagehelp
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