diff --git a/sys/amd64/amd64/vm_machdep.c b/sys/amd64/amd64/vm_machdep.c
--- a/sys/amd64/amd64/vm_machdep.c
+++ b/sys/amd64/amd64/vm_machdep.c
@@ -690,28 +690,3 @@
 	pcb->pcb_fsbase = (register_t)tls_base;
 	return (0);
 }
-
-/*
- * Tell whether this address is in some physical memory region.
- * Currently used by the kernel coredump code in order to avoid
- * dumping the ``ISA memory hole'' which could cause indefinite hangs,
- * or other unpredictable behaviour.
- */
-
-int
-is_physical_memory(vm_paddr_t addr)
-{
-
-#ifdef DEV_ISA
-	/* The ISA ``memory hole''. */
-	if (addr >= 0xa0000 && addr < 0x100000)
-		return 0;
-#endif
-
-	/*
-	 * stuff other tests for known memory-mapped devices (PCI?)
-	 * here
-	 */
-
-	return 1;
-}
diff --git a/sys/i386/i386/vm_machdep.c b/sys/i386/i386/vm_machdep.c
--- a/sys/i386/i386/vm_machdep.c
+++ b/sys/i386/i386/vm_machdep.c
@@ -650,28 +650,3 @@
 
 	return (sf_buf_process_page(m, sf_buf_invalidate));
 }
-
-/*
- * Tell whether this address is in some physical memory region.
- * Currently used by the kernel coredump code in order to avoid
- * dumping the ``ISA memory hole'' which could cause indefinite hangs,
- * or other unpredictable behaviour.
- */
-
-int
-is_physical_memory(vm_paddr_t addr)
-{
-
-#ifdef DEV_ISA
-	/* The ISA ``memory hole''. */
-	if (addr >= 0xa0000 && addr < 0x100000)
-		return 0;
-#endif
-
-	/*
-	 * stuff other tests for known memory-mapped devices (PCI?)
-	 * here
-	 */
-
-	return 1;
-}
diff --git a/sys/powerpc/include/md_var.h b/sys/powerpc/include/md_var.h
--- a/sys/powerpc/include/md_var.h
+++ b/sys/powerpc/include/md_var.h
@@ -58,7 +58,6 @@
 
 void	__syncicache(void *, int);
 
-int	is_physical_memory(vm_offset_t addr);
 int	mem_valid(vm_offset_t addr, int len);
 
 void	decr_init(void);
diff --git a/sys/powerpc/powerpc/vm_machdep.c b/sys/powerpc/powerpc/vm_machdep.c
--- a/sys/powerpc/powerpc/vm_machdep.c
+++ b/sys/powerpc/powerpc/vm_machdep.c
@@ -208,23 +208,6 @@
 
 }
 
-/*
- * Tell whether this address is in some physical memory region.
- * Currently used by the kernel coredump code in order to avoid
- * dumping the ``ISA memory hole'' which could cause indefinite hangs,
- * or other unpredictable behaviour.
- */
-int
-is_physical_memory(vm_offset_t addr)
-{
-
-	/*
-	 * stuff other tests for known memory-mapped devices (PCI?)
-	 * here
-	 */
-	return (1);
-}
-
 /*
  * CPU threading functions related to the VM layer. These could be used
  * to map the SLB bits required for the kernel stack instead of forcing a
diff --git a/sys/x86/include/x86_var.h b/sys/x86/include/x86_var.h
--- a/sys/x86/include/x86_var.h
+++ b/sys/x86/include/x86_var.h
@@ -134,7 +134,6 @@
 void	initializecpucache(void);
 bool	fix_cpuid(void);
 void	fillw(int /*u_short*/ pat, void *base, size_t cnt);
-int	is_physical_memory(vm_paddr_t addr);
 int	isa_nmi(int cd);
 void	handle_ibrs_entry(void);
 void	handle_ibrs_exit(void);