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From: "Mike Durian" <durian@plutotech.com>
To: freebsd-hackers@freebsd.org
Subject: small bugs in pci code
Date: Thu, 07 Nov 1996 11:35:09 -0700
Sender: owner-hackers@freebsd.org
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Precedence: bulk

  I've discovered three bugs in the pci code (at least I believe they
are bugs).  These are in the 2.1.5 release.  Since we've made some
local changes to these files, I don't have proper diffs, but the
changes are very small and isolated.

    1) In pcireg.h, the definitions of PCI_PPB_IOBASE_EXTRACT and
       PCI_PPB_IOLIMIT_EXTRACT should be:

#define PCI_PPB_IOBASE_EXTRACT(x)       (((x) << 8) & 0xF000)
#define PCI_PPB_IOLIMIT_EXTRACT(x)      (((x) << 0) & 0xF000)

       Notice the mask has changed from 0xff00 to 0xf000.  This is
       because the lower nibble is not part of the address, but instead
       determines if the addressing is 16 bit or 32 bit.

    2) Related to #1, the mask that is OR'd with the PCI_PPB_IOLIMIT_EXTRACT
       value should be 0xfff.  It should not be calculated from the
       amount of memory requested.  I don't have a line number for this,
       but it is in pci.c near the PCI_PPB_IOLIMIT_EXTRACT string, which
       only occurs once.  The PCI standard says, "the upper 4 bits of I/O
       Limit register are writeable and correspond to address bits AD[15::12].
       For purpose of address decoding the bridge assumes that the lower 12
       address bits, AD[11::0], of the I/O limit address (not implemented
       in the I/O Limit register) are FFFh."

    3) In the same pci_bus_config() function, there is a section of for
       loop code that begins with the comment, "Read the current mapping,
       and update the pcicb fields."  In this for loop, there is a switch
       statement that handles the two types of mapping: I/O and memory.
       The line:
			switch (data & 7) {
       should read:
			switch (map & 7) {
       The lower three bits that determine the mapping type are found in
       the address value, not the size value.

mike