SEO

re
this fixes the long-standing bug in the i386 dma'ble memory
allocation. in short -- prefer higher physical memory segments
for busses (say pci) rather than exhausting the below-16m
segment that is much more favourable for isa.
please test.
cu

--
paranoic mickey (my employers have changed but, the name has remained)

Index: i386/machdep.c
================================================== =================
RCS file: /cvs/src/sys/arch/i386/i386/machdep.c,v
retrieving revision 1.332
diff -u -r1.332 machdep.c
--- i386/machdep.c 18 Nov 2005 17:11:57 -0000 1.332
+++ i386/machdep.c 21 Nov 2005 18:11:11 -0000
@@ -4160,12 +4166,16 @@
/* Always round the size. */
size = round_page(size);

+ TAILQ_INIT(&mlist);
/*
* Allocate pages from the VM system.
+ * For non-ISA mappings first try higher memory segments.
*/
- TAILQ_INIT(&mlist);
- error = uvm_pglistalloc(size, low, high,
- alignment, boundary, &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0);
+ if (high <= ISA_DMA_BOUNCE_THRESHOLD || (error = uvm_pglistalloc(size,
+ round_page(ISA_DMA_BOUNCE_THRESHOLD), high, alignment, boundary,
+ &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0)))
+ error = uvm_pglistalloc(size, low, high, alignment, boundary,
+ &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0);
if (error)
return (error);

Index: isa/isa_machdep.c
================================================== =================
RCS file: /cvs/src/sys/arch/i386/isa/isa_machdep.c,v
retrieving revision 1.51
diff -u -r1.51 isa_machdep.c
--- isa/isa_machdep.c 29 Nov 2004 20:15:40 -0000 1.51
+++ isa/isa_machdep.c 21 Nov 2005 17:57:20 -0000
@@ -144,11 +144,6 @@

#include "isadma.h"

-/*
- * ISA can only DMA to 0-16M.
- */
-#define ISA_DMA_BOUNCE_THRESHOLD 0x00ffffff
-
extern paddr_t avail_end;

#define IDTVEC(name) __CONCAT(X,name)
Index: isa/isa_machdep.h
================================================== =================
RCS file: /cvs/src/sys/arch/i386/isa/isa_machdep.h,v
retrieving revision 1.19
diff -u -r1.19 isa_machdep.h
--- isa/isa_machdep.h 2 Jun 2003 23:27:47 -0000 1.19
+++ isa/isa_machdep.h 21 Nov 2005 17:57:39 -0000
@@ -83,6 +83,11 @@
#include <machine/bus.h>

/*
+ * ISA can only DMA to 0-16M.
+ */
+#define ISA_DMA_BOUNCE_THRESHOLD 0x00ffffff
+
+/*
* XXX THIS FILE IS A MESS. copyright: berkeley's probably.
* contents from isavar.h and isareg.h, mostly the latter.
* perhaps charles's?