For the cases when loading bzip2-compressed kernels enabled use last

3MB of physical memory for heap instead of range between 1MB and 4MB.
This makes this feature working with PAE and amd64 kernels, which are
loaded at 2MB. Teach i386_copyin() to avoid using range allocated by
heap in such case, so that it won't trash heap in the low memory
conditions.

This should make loading bzip2-compressed kernels/modules/mfs images
generally useable, so that re@ team is welcome to evaluate merits
of using this feature in the installation CDs.

Valuable suggestions by:	jhb

4 files changed, 10 insertions, 6 deletions

diff --git a/sys/boot/i386/libi386/biosmem.c b/sys/boot/i386/libi386/biosmem.c
index 019cf90..6d4f966 100644
--- a/sys/boot/i386/libi386/biosmem.c
+++ b/sys/boot/i386/libi386/biosmem.c
@@ -34,7 +34,7 @@ __FBSDID("$FreeBSD$");
 #include "libi386.h"
 #include "btxv86.h"
 
-vm_offset_t	memtop;
+vm_offset_t	memtop, memtop_copyin;
 u_int32_t	bios_basemem, bios_extmem;
 
 #define SMAPSIG	0x534D4150
@@ -101,7 +101,7 @@ bios_getmem(void)
     }
 
     /* Set memtop to actual top of memory */
-    memtop = 0x100000 + bios_extmem;
+    memtop = memtop_copyin = 0x100000 + bios_extmem;
 
 }    
 
diff --git a/sys/boot/i386/libi386/i386_copy.c b/sys/boot/i386/libi386/i386_copy.c
index e488716..3c05241 100644
--- a/sys/boot/i386/libi386/i386_copy.c
+++ b/sys/boot/i386/libi386/i386_copy.c
@@ -66,7 +66,7 @@ ssize_t
 i386_readin(const int fd, vm_offset_t dest, const size_t len)
 {
 
-    if (dest + len >= memtop) {
+    if (dest + len >= memtop_copyin) {
 	errno = EFBIG;
 	return(-1);
     }
diff --git a/sys/boot/i386/libi386/libi386.h b/sys/boot/i386/libi386/libi386.h
index 670d2cb..4f12161 100644
--- a/sys/boot/i386/libi386/libi386.h
+++ b/sys/boot/i386/libi386/libi386.h
@@ -91,7 +91,10 @@ void	bios_getsmap(void);
 void	bios_getmem(void);
 extern u_int32_t	bios_basemem;				/* base memory in bytes */
 extern u_int32_t	bios_extmem;				/* extended memory in bytes */
-extern vm_offset_t	memtop;
+extern vm_offset_t	memtop;		/* last address of physical memory + 1 */
+extern vm_offset_t	memtop_copyin;	/* memtop less heap size for the cases */
+					/*  when heap is at the top of extended memory */
+					/*  for other cases - just the same as memtop */
 
 int biospci_find_devclass(uint32_t class, int index);
 int biospci_write_config(uint32_t locator, int offset, int width, int val);
diff --git a/sys/boot/i386/loader/main.c b/sys/boot/i386/loader/main.c
index 85d574b..96c40db 100644
--- a/sys/boot/i386/loader/main.c
+++ b/sys/boot/i386/loader/main.c
@@ -92,8 +92,9 @@ main(void)
     bios_getmem();
 
 #ifdef LOADER_BZIP2_SUPPORT
-    heap_top = PTOV(0x400000);
-    heap_bottom = PTOV(0x100000);
+    heap_top = PTOV(memtop_copyin);
+    memtop_copyin -= 0x300000;
+    heap_bottom = PTOV(memtop_copyin);
 #else
     heap_top = (void *)bios_basemem;
     heap_bottom = (void *)end;