[Qemu-devel] Problem booting 2.5 kernel with HZ != 1000

[Qemu-devel] Problem booting 2.5 kernel with HZ != 1000

[Rusty Russell]

Hi Fabrice,

	Setting HZ to any value other than 1000 causes vl to hang for
me (no response to C-x a).  The RT timer is still going off inside vl,
but it doesn't seem to be getting through as a timer interrupt.

BTW, vl compiled with gcc 3.3 gives a Floating Exception, so I
compiled it with 2.95 and it works.

Tried 0.4.1 and CVS.

Here's the output, kernel patch I'm using below.

rusty@bach:~/devel/cvs/qemu$ ./vl -initrd ~/devel/qemu/vl-test/initrd-2.4.20.img ~/devel/kernel/working-2.5.73-bk7-qemu-page-offset/arch/i386/boot/bzImage
Connected to host network interface: tun0
/etc/vl-ifup: could not launch network script for 'tun0'
Uncompressing Linux... Ok, booting the kernel.
Linux version 2.5.73-bk7 (rusty@bach) (gcc version 3.2.3 (Debian)) #13 Tue Jul 1 15:03:18 EST 2003
Video mode to be used for restore is 0
BIOS-provided physical RAM map:
 BIOS-88: 0000000000000000 - 000000000009f000 (usable)
 BIOS-88: 0000000000100000 - 0000000002000000 (usable)
32MB LOWMEM available.
On node 0 totalpages: 8192
  DMA zone: 4096 pages, LIFO batch:1
  Normal zone: 4096 pages, LIFO batch:1
  HighMem zone: 0 pages, LIFO batch:1
Building zonelist for node : 0
Kernel command line: 
Initializing CPU#0
PID hash table entries: 256 (order 8: 2048 bytes)
Detected 697.116 MHz processor.
[ hang ]

--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

Name: QEMU CONFIG Patch
Author: Rusty Russell
Status: Trivial

D: Convenient patch based on Fabrice Bellard's documentation on how to
D: boot an x86 kernel under qemu 0.4.  Adjusts PAGE_OFFSET and HZ value.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.73-bk7/arch/i386/Kconfig working-2.5.73-bk7-qemu-page-offset/arch/i386/Kconfig
--- linux-2.5.73-bk7/arch/i386/Kconfig	2003-06-30 11:46:42.000000000 +1000
+++ working-2.5.73-bk7-qemu-page-offset/arch/i386/Kconfig	2003-06-30 15:54:49.000000000 +1000
@@ -307,6 +307,14 @@ config X86_GENERIC
 	  when it has moderate overhead. This is intended for generic 
 	  distributions kernels.
 
+config QEMU
+	bool "Kernel to run under QEMU"
+	depends on EXPERIMENTAL
+	help
+	  Select this if you want to boot the kernel inside qemu, the
+	  x86 emulator.  See http://fabrice.bellard.free.fr/qemu/.
+	  Say N.
+
 #
 # Define implied options from the CPU selection here
 #
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.73-bk7/arch/i386/vmlinux.lds.S working-2.5.73-bk7-qemu-page-offset/arch/i386/vmlinux.lds.S
--- linux-2.5.73-bk7/arch/i386/vmlinux.lds.S	2003-06-15 11:29:47.000000000 +1000
+++ working-2.5.73-bk7-qemu-page-offset/arch/i386/vmlinux.lds.S	2003-06-30 15:54:49.000000000 +1000
@@ -3,14 +3,15 @@
  */
 
 #include <asm-generic/vmlinux.lds.h>
-	
+#include <asm/page.h>
+		
 OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
 OUTPUT_ARCH(i386)
 ENTRY(startup_32)
 jiffies = jiffies_64;
 SECTIONS
 {
-  . = 0xC0000000 + 0x100000;
+  . = __PAGE_OFFSET + 0x100000;
   /* read-only */
   _text = .;			/* Text and read-only data */
   .text : {
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.73-bk7/include/asm-i386/page.h working-2.5.73-bk7-qemu-page-offset/include/asm-i386/page.h
--- linux-2.5.73-bk7/include/asm-i386/page.h	2003-04-08 11:14:55.000000000 +1000
+++ working-2.5.73-bk7-qemu-page-offset/include/asm-i386/page.h	2003-06-30 15:54:49.000000000 +1000
@@ -10,10 +10,10 @@
 #define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
 
 #ifdef __KERNEL__
-#ifndef __ASSEMBLY__
-
 #include <linux/config.h>
 
+#ifndef __ASSEMBLY__
+
 #ifdef CONFIG_X86_USE_3DNOW
 
 #include <asm/mmx.h>
@@ -115,12 +115,19 @@ static __inline__ int get_order(unsigned
 #endif /* __ASSEMBLY__ */
 
 #ifdef __ASSEMBLY__
+#ifdef CONFIG_QEMU
+#define __PAGE_OFFSET		(0x90000000)
+#else
 #define __PAGE_OFFSET		(0xC0000000)
+#endif /* QEMU */
+#else
+#ifdef CONFIG_QEMU
+#define __PAGE_OFFSET		(0x90000000UL)
 #else
 #define __PAGE_OFFSET		(0xC0000000UL)
+#endif /* QEMU */
 #endif
 
-
 #define PAGE_OFFSET		((unsigned long)__PAGE_OFFSET)
 #define VMALLOC_RESERVE		((unsigned long)__VMALLOC_RESERVE)
 #define MAXMEM			(-__PAGE_OFFSET-__VMALLOC_RESERVE)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.73-bk7/include/asm-i386/param.h working-2.5.73-bk7-qemu-page-offset/include/asm-i386/param.h
--- linux-2.5.73-bk7/include/asm-i386/param.h	2003-01-02 12:07:44.000000000 +1100
+++ working-2.5.73-bk7-qemu-page-offset/include/asm-i386/param.h	2003-07-01 14:59:57.000000000 +1000
@@ -2,7 +2,11 @@
 #define _ASMi386_PARAM_H
 
 #ifdef __KERNEL__
-# define HZ		1000		/* Internal kernel timer frequency */
+# ifdef CONFIG_QEMU
+#  define HZ		100
+# else
+#  define HZ		1000		/* Internal kernel timer frequency */
+# endif
 # define USER_HZ	100		/* .. some user interfaces are in "ticks" */
 # define CLOCKS_PER_SEC	(USER_HZ)	/* like times() */
 #endif