Index: sys/amd64/include/vmparam.h
===================================================================
--- sys/amd64/include/vmparam.h
+++ sys/amd64/include/vmparam.h
@@ -110,7 +110,9 @@
 #define	VM_NFREELIST		3
 #define	VM_FREELIST_DEFAULT	0
 #define	VM_FREELIST_DMA32	1
-#define	VM_FREELIST_ISADMA	2
+#define	VM_FREELIST_LOWMEM	2
+
+#define VM_LOWMEM_BOUNDARY	(16 << 10)	/* 16MB ISA DMA limit */
 
 /*
  * Create the DMA32 free list only if the number of physical pages above
Index: sys/arm64/include/vmparam.h
===================================================================
--- sys/arm64/include/vmparam.h
+++ sys/arm64/include/vmparam.h
@@ -67,10 +67,7 @@
 #define	VM_PHYSSEG_SPARSE
 
 /*
- * The number of PHYSSEG entries must be one greater than the number
- * of phys_avail entries because the phys_avail entry that spans the
- * largest physical address that is accessible by ISA DMA is split
- * into two PHYSSEG entries.
+ * The number of PHYSSEG entries.
  */
 #define	VM_PHYSSEG_MAX		64
 
@@ -85,14 +82,11 @@
 #define	VM_FREEPOOL_DIRECT	1
 
 /*
- * Create two free page lists: VM_FREELIST_DEFAULT is for physical
- * pages that are above the largest physical address that is
- * accessible by ISA DMA and VM_FREELIST_ISADMA is for physical pages
- * that are below that address.
+ * Create oone free page lists: VM_FREELIST_DEFAULT is for all physical
+ * pages.
  */
-#define	VM_NFREELIST		2
+#define	VM_NFREELIST		1
 #define	VM_FREELIST_DEFAULT	0
-#define	VM_FREELIST_ISADMA	1
 
 /*
  * An allocation size of 16MB is supported in order to optimize the
Index: sys/i386/include/vmparam.h
===================================================================
--- sys/i386/include/vmparam.h
+++ sys/i386/include/vmparam.h
@@ -97,12 +97,14 @@
 /*
  * Create two free page lists: VM_FREELIST_DEFAULT is for physical
  * pages that are above the largest physical address that is
- * accessible by ISA DMA and VM_FREELIST_ISADMA is for physical pages
+ * accessible by ISA DMA and VM_FREELIST_LOWMEM is for physical pages
  * that are below that address.
  */
 #define	VM_NFREELIST		2
 #define	VM_FREELIST_DEFAULT	0
-#define	VM_FREELIST_ISADMA	1
+#define	VM_FREELIST_LOWMEM	1
+
+#define VM_LOWMEM_BOUNDARY	(16 << 10)	/* 16MB ISA DMA limit */
 
 /*
  * The largest allocation size is 2MB under PAE and 4MB otherwise.
Index: sys/riscv/include/vmparam.h
===================================================================
--- sys/riscv/include/vmparam.h
+++ sys/riscv/include/vmparam.h
@@ -67,10 +67,7 @@
 #define	VM_PHYSSEG_SPARSE
 
 /*
- * The number of PHYSSEG entries must be one greater than the number
- * of phys_avail entries because the phys_avail entry that spans the
- * largest physical address that is accessible by ISA DMA is split
- * into two PHYSSEG entries.
+ * The number of PHYSSEG entries.
  */
 #define	VM_PHYSSEG_MAX		64
 
@@ -85,14 +82,11 @@
 #define	VM_FREEPOOL_DIRECT	1
 
 /*
- * Create two free page lists: VM_FREELIST_DEFAULT is for physical
- * pages that are above the largest physical address that is
- * accessible by ISA DMA and VM_FREELIST_ISADMA is for physical pages
- * that are below that address.
+ * Create one free page list: VM_FREELIST_DEFAULT is for all physical
+ * pages.
  */
-#define	VM_NFREELIST		2
+#define	VM_NFREELIST		1
 #define	VM_FREELIST_DEFAULT	0
-#define	VM_FREELIST_ISADMA	1
 
 /*
  * An allocation size of 16MB is supported in order to optimize the
Index: sys/sparc64/include/vmparam.h
===================================================================
--- sys/sparc64/include/vmparam.h
+++ sys/sparc64/include/vmparam.h
@@ -87,14 +87,11 @@
 #define	VM_FREEPOOL_DIRECT	1
 
 /*
- * Create two free page lists: VM_FREELIST_DEFAULT is for physical
- * pages that are above the largest physical address that is
- * accessible by ISA DMA and VM_FREELIST_ISADMA is for physical pages
- * that are below that address.
+ * Create one free page lists: VM_FREELIST_DEFAULT is for all physical
+ * pages.
  */
-#define	VM_NFREELIST		2
+#define	VM_NFREELIST		1
 #define	VM_FREELIST_DEFAULT	0
-#define	VM_FREELIST_ISADMA	1
 
 /*
  * An allocation size of 16MB is supported in order to optimize the
Index: sys/vm/vm_phys.c
===================================================================
--- sys/vm/vm_phys.c
+++ sys/vm/vm_phys.c
@@ -115,9 +115,6 @@
 
 CTASSERT(VM_FREELIST_DEFAULT == 0);
 
-#ifdef VM_FREELIST_ISADMA
-#define	VM_ISADMA_BOUNDARY	16777216
-#endif
 #ifdef VM_FREELIST_DMA32
 #define	VM_DMA32_BOUNDARY	((vm_paddr_t)1 << 32)
 #endif
@@ -126,9 +123,6 @@
  * Enforce the assumptions made by vm_phys_add_seg() and vm_phys_init() about
  * the ordering of the free list boundaries.
  */
-#if defined(VM_ISADMA_BOUNDARY) && defined(VM_LOWMEM_BOUNDARY)
-CTASSERT(VM_ISADMA_BOUNDARY < VM_LOWMEM_BOUNDARY);
-#endif
 #if defined(VM_LOWMEM_BOUNDARY) && defined(VM_DMA32_BOUNDARY)
 CTASSERT(VM_LOWMEM_BOUNDARY < VM_DMA32_BOUNDARY);
 #endif
@@ -442,12 +436,6 @@
 	 * list boundaries.
 	 */
 	paddr = start;
-#ifdef	VM_FREELIST_ISADMA
-	if (paddr < VM_ISADMA_BOUNDARY && end > VM_ISADMA_BOUNDARY) {
-		vm_phys_create_seg(paddr, VM_ISADMA_BOUNDARY);
-		paddr = VM_ISADMA_BOUNDARY;
-	}
-#endif
 #ifdef	VM_FREELIST_LOWMEM
 	if (paddr < VM_LOWMEM_BOUNDARY && end > VM_LOWMEM_BOUNDARY) {
 		vm_phys_create_seg(paddr, VM_LOWMEM_BOUNDARY);
@@ -486,11 +474,6 @@
 	npages = 0;
 	for (segind = vm_phys_nsegs - 1; segind >= 0; segind--) {
 		seg = &vm_phys_segs[segind];
-#ifdef	VM_FREELIST_ISADMA
-		if (seg->end <= VM_ISADMA_BOUNDARY)
-			vm_freelist_to_flind[VM_FREELIST_ISADMA] = 1;
-		else
-#endif
 #ifdef	VM_FREELIST_LOWMEM
 		if (seg->end <= VM_LOWMEM_BOUNDARY)
 			vm_freelist_to_flind[VM_FREELIST_LOWMEM] = 1;
@@ -541,13 +524,6 @@
 #else
 		seg->first_page = PHYS_TO_VM_PAGE(seg->start);
 #endif
-#ifdef	VM_FREELIST_ISADMA
-		if (seg->end <= VM_ISADMA_BOUNDARY) {
-			flind = vm_freelist_to_flind[VM_FREELIST_ISADMA];
-			KASSERT(flind >= 0,
-			    ("vm_phys_init: ISADMA flind < 0"));
-		} else
-#endif
 #ifdef	VM_FREELIST_LOWMEM
 		if (seg->end <= VM_LOWMEM_BOUNDARY) {
 			flind = vm_freelist_to_flind[VM_FREELIST_LOWMEM];