Re: 2.6.22-rc1-mm1: boot failure under qemu

[H. Peter Anvin]

Jeremy Fitzhardinge wrote:
> H. Peter Anvin wrote:
>> Okay, I've established that this is a bug in the Qemu kernel loader: the
>> Qemu loader puts zero in the loadflags, which is wrong no matter how you
>> slice it.
>>
>> I have checked in a workaround in the git.newsetup tree; the workaround
>> is to rely on a compile-time value for load low/load high instead of
>> looking at loadflags.
>>   
> 
> Can you post a patch to try?
> 

Cumulative diff from -rc1-mm1.

	-hpa
diff --git a/arch/i386/boot/Makefile b/arch/i386/boot/Makefile
index 6792d09..a2b3f93 100644
--- a/arch/i386/boot/Makefile
+++ b/arch/i386/boot/Makefile
@@ -62,6 +62,7 @@ AFLAGS		:= $(CFLAGS) -D__ASSEMBLY__
 $(obj)/zImage:  IMAGE_OFFSET := 0x1000
 $(obj)/zImage:  EXTRA_AFLAGS := $(SVGA_MODE) $(RAMDISK)
 $(obj)/bzImage: IMAGE_OFFSET := 0x100000
+$(obj)/bzImage: EXTRA_CFLAGS := -D__BIG_KERNEL__
 $(obj)/bzImage: EXTRA_AFLAGS := $(SVGA_MODE) $(RAMDISK) -D__BIG_KERNEL__
 $(obj)/bzImage: BUILDFLAGS   := -b
 
diff --git a/arch/i386/boot/main.c b/arch/i386/boot/main.c
index 5f4d99d..873c777 100644
--- a/arch/i386/boot/main.c
+++ b/arch/i386/boot/main.c
@@ -112,6 +112,10 @@ void main(void)
 	if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 		heap_end = (char *)(boot_params.hdr.heap_end_ptr
 				    +0x200-STACK_SIZE);
+	} else {
+		/* Boot protocol 2.00 only, no heap available */
+		puts("WARNING: Ancient bootloader, some functionality "
+		     "may be limited!\n");
 	}
 
 	/* Make sure we have all the proper CPU support */
diff --git a/arch/i386/boot/memory.c b/arch/i386/boot/memory.c
index 8a82aa9..d7b250b 100644
--- a/arch/i386/boot/memory.c
+++ b/arch/i386/boot/memory.c
@@ -30,7 +30,7 @@ static int detect_memory_e820(void)
 		size = sizeof(struct e820entry);
 		id = SMAP;
 		asm("int $0x15; setc %0"
-		    : "=dm" (err), "+b" (next), "+d" (id), "+c" (size),
+		    : "=am" (err), "+b" (next), "+d" (id), "+c" (size),
 		      "=m" (*desc)
 		    : "D" (desc), "a" (0xe820));
 
diff --git a/arch/i386/boot/pm.c b/arch/i386/boot/pm.c
index 1c586f1..7af65f9 100644
--- a/arch/i386/boot/pm.c
+++ b/arch/i386/boot/pm.c
@@ -41,12 +41,13 @@ static void realmode_switch_hook(void)
  */
 static void move_kernel_around(void)
 {
+	/* Note: rely on the compile-time option here rather than
+	   the LOADED_HIGH flag.  The Qemu kernel loader unconditionally
+	   sets the loadflags to zero. */
+#ifndef __BIG_KERNEL__
 	u16 dst_seg, src_seg;
 	u32 syssize;
 
-	if (boot_params.hdr.loadflags & LOADED_HIGH)
-		return;
-
 	dst_seg =  0x1000 >> 4;
 	src_seg = 0x10000 >> 4;
 	syssize = boot_params.hdr.syssize; /* Size in 16-byte paragraps */
@@ -72,6 +73,7 @@ static void move_kernel_around(void)
 		dst_seg += paras;
 		src_seg += paras;
 	}
+#endif
 }
 
 /*