6b7f805e47
to see if it was malloc()ed first" bug. In bus_dmamap_create(), one of two things can happen: either we need to allocate a special map due to some manner of bounce buffering requirement, or we can DMA a buffer in place. On the x86 platform, the "in place" case results in bus_dmamap_create() returning a dmamap of NULL. The bus_dmamap_destroy() routine later checks for NULL and won't bother free()ing the map if it detects this condition. But on the alpha, we don't use NULL, we use a statically allocated map called nobounce_dmamap(). Unfortunately, bus_dmamap_destroy() does not handle the condition where we attempt to destroy such a map: it tries to free() the dmamap, which causes a panic. Fix: test that map != &nobounce_dmamap before trying to free() it. With this fix, my busdma-ified if_sis driver works on the alpha. I'm a bit alarmed that I'm the first person ever to trip over this bug, since we have been using busdma on the alpha for a while, and since it sort of screams out "Hi! I'm a bug! Booga-booga!" when you look at it. (Somewhere, somebody will say: "But Bill, why don't you just not bother destroying the maps in this case." Because the API is supposed to be a) symetrical and b) opaque to the caller. I can't know whether it's safe to skip the bus_dmamap_destroy() step or not without sticking my fingers into unsafe places, which is what I wanted to avoid in the first place.)
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you have to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/i386/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/User commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberosIV Kerberos package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/handbook/synching.html