Re: [Qemu-devel] qemu on 2.6.0-rc1

[Rusty Russell <rusty@rustcorp.com.au>]

In message <20040105223155.GA14669@best.ms.philips.com> you write:
> Hi,
> 
> I try to run qemu-fast on Linux kernel 2.6.0-rc1. I could not find the
> things which I should change in the documentation:

Here's my patch, included below.  2.6.0 requires the vsyscall area to
move as well.

Sure, you can run the non-fast qemu, but it's MUCH slower.

Andrew?   This patch also has the benifit of moving all the constants
to one place, as well as adding a CONFIG_QEMU option.  I use it for
testing all the time.

Thanks,
Rusty.

Name: QEMU CONFIG Patch
Author: Rusty Russell
Status: Tested on 2.6.0

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

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/Kconfig .32324-linux-2.6.0.updated/arch/i386/Kconfig
--- .32324-linux-2.6.0/arch/i386/Kconfig	2003-10-09 18:02:48.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/Kconfig	2003-12-26 16:46:49.000000000 +1100
@@ -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-fast,
+	  the non-mmu version of 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 .32324-linux-2.6.0/arch/i386/kernel/Makefile .32324-linux-2.6.0.updated/arch/i386/kernel/Makefile
--- .32324-linux-2.6.0/arch/i386/kernel/Makefile	2003-09-29 10:25:15.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/Makefile	2003-12-26 16:46:49.000000000 +1100
@@ -46,12 +46,14 @@ quiet_cmd_syscall = SYSCALL $@
       cmd_syscall = $(CC) -nostdlib $(SYSCFLAGS_$(@F)) \
 		          -Wl,-T,$(filter-out FORCE,$^) -o $@
 
+export AFLAGS_vsyscall.lds.o += -P -C -U$(ARCH)
+
 vsyscall-flags = -shared -s -Wl,-soname=linux-gate.so.1
 SYSCFLAGS_vsyscall-sysenter.so	= $(vsyscall-flags)
 SYSCFLAGS_vsyscall-int80.so	= $(vsyscall-flags)
 
 $(obj)/vsyscall-int80.so $(obj)/vsyscall-sysenter.so: \
-$(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
+$(obj)/vsyscall-%.so: $(src)/vsyscall.lds.s $(obj)/vsyscall-%.o FORCE
 	$(call if_changed,syscall)
 
 # We also create a special relocatable object that should mirror the symbol
@@ -62,5 +64,5 @@ $(obj)/built-in.o: $(obj)/vsyscall-syms.
 $(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
 
 SYSCFLAGS_vsyscall-syms.o = -r
-$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds $(obj)/vsyscall-sysenter.o FORCE
+$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds.s $(obj)/vsyscall-sysenter.o FORCE
 	$(call if_changed,syscall)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/kernel/vmlinux.lds.S .32324-linux-2.6.0.updated/arch/i386/kernel/vmlinux.lds.S
--- .32324-linux-2.6.0/arch/i386/kernel/vmlinux.lds.S	2003-09-22 10:27:28.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/vmlinux.lds.S	2003-12-26 16:46:49.000000000 +1100
@@ -3,6 +3,7 @@
  */
 
 #include <asm-generic/vmlinux.lds.h>
+#include <asm/page.h>
 	
 OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
 OUTPUT_ARCH(i386)
@@ -10,7 +11,7 @@ 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 .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds
--- .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds	2003-09-22 10:07:26.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds	1970-01-01 10:00:00.000000000 +1000
@@ -1,67 +0,0 @@
-/*
- * Linker script for vsyscall DSO.  The vsyscall page is an ELF shared
- * object prelinked to its virtual address, and with only one read-only
- * segment (that fits in one page).  This script controls its layout.
- */
-
-/* This must match <asm/fixmap.h>.  */
-VSYSCALL_BASE = 0xffffe000;
-
-SECTIONS
-{
-  . = VSYSCALL_BASE + SIZEOF_HEADERS;
-
-  .hash           : { *(.hash) }		:text
-  .dynsym         : { *(.dynsym) }
-  .dynstr         : { *(.dynstr) }
-  .gnu.version    : { *(.gnu.version) }
-  .gnu.version_d  : { *(.gnu.version_d) }
-  .gnu.version_r  : { *(.gnu.version_r) }
-
-  /* This linker script is used both with -r and with -shared.
-     For the layouts to match, we need to skip more than enough
-     space for the dynamic symbol table et al.  If this amount
-     is insufficient, ld -shared will barf.  Just increase it here.  */
-  . = VSYSCALL_BASE + 0x400;
-
-  .text           : { *(.text) }		:text =0x90909090
-
-  .eh_frame_hdr   : { *(.eh_frame_hdr) }	:text :eh_frame_hdr
-  .eh_frame       : { KEEP (*(.eh_frame)) }	:text
-  .dynamic        : { *(.dynamic) }		:text :dynamic
-  .useless        : {
-  	*(.got.plt) *(.got)
-	*(.data .data.* .gnu.linkonce.d.*)
-	*(.dynbss)
-	*(.bss .bss.* .gnu.linkonce.b.*)
-  }						:text
-}
-
-/*
- * We must supply the ELF program headers explicitly to get just one
- * PT_LOAD segment, and set the flags explicitly to make segments read-only.
- */
-PHDRS
-{
-  text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
-  dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
-  eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
-}
-
-/*
- * This controls what symbols we export from the DSO.
- */
-VERSION
-{
-  LINUX_2.5 {
-    global:
-    	__kernel_vsyscall;
-    	__kernel_sigreturn;
-    	__kernel_rt_sigreturn;
-
-    local: *;
-  };
-}
-
-/* The ELF entry point can be used to set the AT_SYSINFO value.  */
-ENTRY(__kernel_vsyscall);
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds.S .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds.S
--- .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds.S	1970-01-01 10:00:00.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds.S	2003-12-26 16:46:49.000000000 +1100
@@ -0,0 +1,67 @@
+/*
+ * Linker script for vsyscall DSO.  The vsyscall page is an ELF shared
+ * object prelinked to its virtual address, and with only one read-only
+ * segment (that fits in one page).  This script controls its layout.
+ */
+#include <asm/fixmap.h>
+	
+VSYSCALL_BASE = __FIXADDR_TOP - 0x1000;
+
+SECTIONS
+{
+  . = VSYSCALL_BASE + SIZEOF_HEADERS;
+
+  .hash           : { *(.hash) }		:text
+  .dynsym         : { *(.dynsym) }
+  .dynstr         : { *(.dynstr) }
+  .gnu.version    : { *(.gnu.version) }
+  .gnu.version_d  : { *(.gnu.version_d) }
+  .gnu.version_r  : { *(.gnu.version_r) }
+
+  /* This linker script is used both with -r and with -shared.
+     For the layouts to match, we need to skip more than enough
+     space for the dynamic symbol table et al.  If this amount
+     is insufficient, ld -shared will barf.  Just increase it here.  */
+  . = VSYSCALL_BASE + 0x400;
+
+  .text           : { *(.text) }		:text =0x90909090
+
+  .eh_frame_hdr   : { *(.eh_frame_hdr) }	:text :eh_frame_hdr
+  .eh_frame       : { KEEP (*(.eh_frame)) }	:text
+  .dynamic        : { *(.dynamic) }		:text :dynamic
+  .useless        : {
+  	*(.got.plt) *(.got)
+	*(.data .data.* .gnu.linkonce.d.*)
+	*(.dynbss)
+	*(.bss .bss.* .gnu.linkonce.b.*)
+  }						:text
+}
+
+/*
+ * We must supply the ELF program headers explicitly to get just one
+ * PT_LOAD segment, and set the flags explicitly to make segments read-only.
+ */
+PHDRS
+{
+  text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
+  dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
+  eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
+}
+
+/*
+ * This controls what symbols we export from the DSO.
+ */
+VERSION
+{
+  LINUX_2.5 {
+    global:
+    	__kernel_vsyscall;
+    	__kernel_sigreturn;
+    	__kernel_rt_sigreturn;
+
+    local: *;
+  };
+}
+
+/* The ELF entry point can be used to set the AT_SYSINFO value.  */
+ENTRY(__kernel_vsyscall);
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/include/asm-i386/fixmap.h .32324-linux-2.6.0.updated/include/asm-i386/fixmap.h
--- .32324-linux-2.6.0/include/asm-i386/fixmap.h	2003-09-22 10:09:12.000000000 +1000
+++ .32324-linux-2.6.0.updated/include/asm-i386/fixmap.h	2003-12-26 16:46:49.000000000 +1100
@@ -14,6 +14,19 @@
 #define _ASM_FIXMAP_H
 
 #include <linux/config.h>
+
+/* used by vmalloc.c, vsyscall.lds.S.
+ *
+ * Leave one empty page between vmalloc'ed areas and
+ * the start of the fixmap.
+ */
+#ifdef CONFIG_QEMU
+#define __FIXADDR_TOP	0xa7fff000
+#else
+#define __FIXADDR_TOP	0xfffff000
+#endif
+
+#ifndef __ASSEMBLY__
 #include <linux/kernel.h>
 #include <asm/acpi.h>
 #include <asm/apicdef.h>
@@ -94,13 +107,8 @@ extern void __set_fixmap (enum fixed_add
 #define clear_fixmap(idx) \
 		__set_fixmap(idx, 0, __pgprot(0))
 
-/*
- * used by vmalloc.c.
- *
- * Leave one empty page between vmalloc'ed areas and
- * the start of the fixmap.
- */
-#define FIXADDR_TOP	(0xfffff000UL)
+#define FIXADDR_TOP	((unsigned long)__FIXADDR_TOP)
+
 #define __FIXADDR_SIZE	(__end_of_permanent_fixed_addresses << PAGE_SHIFT)
 #define FIXADDR_START	(FIXADDR_TOP - __FIXADDR_SIZE)
 
@@ -145,4 +153,5 @@ static inline unsigned long virt_to_fix(
 	return __virt_to_fix(vaddr);
 }
 
+#endif /* !__ASSEMBLY__ */
 #endif
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/include/asm-i386/page.h .32324-linux-2.6.0.updated/include/asm-i386/page.h
--- .32324-linux-2.6.0/include/asm-i386/page.h	2003-09-22 10:06:42.000000000 +1000
+++ .32324-linux-2.6.0.updated/include/asm-i386/page.h	2003-12-26 16:46:49.000000000 +1100
@@ -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 .32324-linux-2.6.0/include/asm-i386/param.h .32324-linux-2.6.0.updated/include/asm-i386/param.h
--- .32324-linux-2.6.0/include/asm-i386/param.h	2003-09-21 17:26:06.000000000 +1000
+++ .32324-linux-2.6.0.updated/include/asm-i386/param.h	2003-12-26 16:46:49.000000000 +1100
@@ -2,7 +2,12 @@
 #define _ASMi386_PARAM_H
 
 #ifdef __KERNEL__
-# define HZ		1000		/* Internal kernel timer frequency */
+# include <linux/config.h>
+# 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
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.