Rework memory mapping reservation

* i386/i386/vm_param.h (VM_KERNEL_MAP_SIZE): Define to 192MiB.
* i386/i386at/model_dep.c (mem_size_init): Use VM_KERNEL_MAP_SIZE instead of
1/6 factor.
* i386/intel/pmap.c (morevm): Remove.
(pmap_bootstrap): Use VM_KERNEL_MAP_SIZE instead of morevm.

3 files changed, 12 insertions, 10 deletions

diff --git a/i386/i386/vm_param.h b/i386/i386/vm_param.h
index 95df604..b515a9e 100644
--- a/i386/i386/vm_param.h
+++ b/i386/i386/vm_param.h
@@ -27,7 +27,7 @@
 #include <mach/vm_param.h>
 #include <xen/public/xen.h>
 
-/* The kernel address space is 1GB, starting at virtual address 0.  */
+/* The kernel address space is usually 1GB, usually starting at virtual address 0.  */
 #ifdef	MACH_XEN
 #define VM_MIN_KERNEL_ADDRESS	0x20000000UL
 #else	/* MACH_XEN */
@@ -45,6 +45,9 @@
 #define VM_MAX_KERNEL_ADDRESS	(LINEAR_MAX_KERNEL_ADDRESS - LINEAR_MIN_KERNEL_ADDRESS + VM_MIN_KERNEL_ADDRESS)
 #endif	/* MACH_XEN */
 
+/* Reserve mapping room for kmem_suballoc calls. */
+#define VM_KERNEL_MAP_SIZE (192 * 1024 * 1024)
+
 /* The kernel virtual address space is actually located
    at high linear addresses.
    This is the kernel address range in linear addresses.  */
diff --git a/i386/i386at/model_dep.c b/i386/i386at/model_dep.c
index 4e7093c..f6e797c 100644
--- a/i386/i386at/model_dep.c
+++ b/i386/i386at/model_dep.c
@@ -261,6 +261,8 @@ void db_reset_cpu(void)
 void
 mem_size_init(void)
 {
+	vm_offset_t max_phys_size;
+
 	/* Physical memory on all PCs starts at physical address 0.
 	   XX make it a constant.  */
 	phys_first_addr = 0;
@@ -285,12 +287,13 @@ mem_size_init(void)
 	printf("AT386 boot: physical memory from 0x%x to 0x%x\n",
 	       phys_first_addr, phys_last_addr);
 
-	/* Reserve 1/6 of the memory address space for virtual mappings.
+	/* Reserve room for virtual mappings.
 	 * Yes, this loses memory.  Blame i386.  */
-	if (phys_last_addr > ((VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 6) * 5) {
-		phys_last_addr = ((VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 6) * 5;
+	max_phys_size = VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS - VM_KERNEL_MAP_SIZE;
+	if (phys_last_addr - phys_first_addr > max_phys_size) {
+		phys_last_addr = phys_first_addr + max_phys_size;
 		printf("Truncating memory size to %dMiB\n", (phys_last_addr - phys_first_addr) / (1024 * 1024));
-		/* TODO Xen: free lost memory */
+		/* TODO Xen: be nice, free lost memory */
 	}
 
 	phys_first_addr = round_page(phys_first_addr);
diff --git a/i386/intel/pmap.c b/i386/intel/pmap.c
index 0b8ae90..c15538f 100644
--- a/i386/intel/pmap.c
+++ b/i386/intel/pmap.c
@@ -155,9 +155,6 @@ boolean_t	pmap_initialized = FALSE;
 vm_offset_t kernel_virtual_start;
 vm_offset_t kernel_virtual_end;
 
-/* XXX stupid fixed limit - get rid */
-vm_size_t morevm = 128 * 1024 * 1024;	/* VM space for kernel map */
-
 /*
  *	Index into pv_head table, its lock bits, and the modify/reference
  *	bits starting at phys_first_addr.
@@ -620,8 +617,7 @@ void pmap_bootstrap()
 	 * and extends to a stupid arbitrary limit beyond that.
 	 */
 	kernel_virtual_start = phystokv(phys_last_addr);
-	kernel_virtual_end = phystokv(phys_last_addr) + morevm
-		+ (phys_last_addr - phys_first_addr);
+	kernel_virtual_end = phystokv(phys_last_addr) + VM_KERNEL_MAP_SIZE;
 
 	if (kernel_virtual_end < kernel_virtual_start
 			|| kernel_virtual_end > VM_MAX_KERNEL_ADDRESS)