[Midnightbsd-cvs] src [8181] trunk/sys/x86/x86/busdma_machdep.c: Allow static DMA allocations that allow for enough segments to do page-sized

[laffer1 at midnightbsd.org]

Revision: 8181
          http://svnweb.midnightbsd.org/src/?rev=8181
Author:   laffer1
Date:     2016-09-16 22:51:41 -0400 (Fri, 16 Sep 2016)
Log Message:
-----------
Allow static DMA allocations that allow for enough segments to do page-sized
segments for the entire allocation to use kmem_alloc_attr() to allocate
KVM rather than using kmem_alloc_contig().  This avoids requiring
a single physically contiguous chunk in this case.

Modified Paths:
--------------
    trunk/sys/x86/x86/busdma_machdep.c

Modified: trunk/sys/x86/x86/busdma_machdep.c
===================================================================
--- trunk/sys/x86/x86/busdma_machdep.c	2016-09-17 02:50:30 UTC (rev 8180)
+++ trunk/sys/x86/x86/busdma_machdep.c	2016-09-17 02:51:41 UTC (rev 8181)
@@ -541,13 +541,14 @@
 	    dmat->lowaddr >= ptoa((vm_paddr_t)Maxmem) &&
 	    attr == VM_MEMATTR_DEFAULT) {
 		*vaddr = malloc(dmat->maxsize, M_DEVBUF, mflags);
+	} else if (dmat->nsegments >= btoc(dmat->maxsize) &&
+	    dmat->alignment <= PAGE_SIZE &&
+	    (dmat->boundary == 0 || dmat->boundary >= dmat->lowaddr)) {
+		/* Page-based multi-segment allocations allowed */
+		*vaddr = (void *)kmem_alloc_attr(kernel_map, dmat->maxsize,
+		    mflags, 0ul, dmat->lowaddr, attr);
+		*mapp = &contig_dmamap;
 	} else {
-		/*
-		 * XXX Use Contigmalloc until it is merged into this facility
-		 *     and handles multi-seg allocations.  Nobody is doing
-		 *     multi-seg allocations yet though.
-		 * XXX Certain AGP hardware does.
-		 */
 		*vaddr = (void *)kmem_alloc_contig(kernel_map, dmat->maxsize,
 		    mflags, 0ul, dmat->lowaddr, dmat->alignment ?
 		    dmat->alignment : 1ul, dmat->boundary, attr);