[PATCH] bootsect removal

This is the "boot sector removal" patch for i386 updated for Linux
2.5.63-bk7.  The only change against the 2.5.59 version is that the
FDOPTS Makefile variable, which lets one create a floppy image with
arbitrary kernel options, has been merged from the x86-64 version, and
the comments have been updated.

The patch removes the in-kernel boot sector, which these days rarely
work correctly (it only supports up to 1 MB kernels, and only work on
legacy floppies -- not on IDE or USB devices, nor on any kind of
emulated devices like El Torito), replaces it with a placeholder stub,
and sets up the Makefile targets to create floppies or floppy images
using SYSLINUX.  The FDOPTS Makefile variable can be used to set
kernel command line options (thanks to a suggestion by Andi Kleen.)

Note that the same change has already been applied to the x86-64
architecture.  The last hunk of the patch corrects a comment in that
architecture.

arch/i386/Makefile

@@ -92,7 +92,8 @@ AFLAGS += $(mflags-y)
 
 boot := arch/i386/boot
 
-.PHONY: zImage bzImage compressed zlilo bzlilo zdisk bzdisk install
+.PHONY: zImage bzImage compressed zlilo bzlilo \
+	zdisk bzdisk fdimage fdimage144 fdimage288 install
 
 all: bzImage
 
@@ -110,8 +111,8 @@ zlilo bzlilo: vmlinux
 zdisk bzdisk: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) zdisk
 
-install: vmlinux
-	$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) install
+install fdimage fdimage144 fdimage288: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) $@
 
 archclean:
 	$(Q)$(MAKE) $(clean)=arch/i386/boot
@@ -122,5 +123,8 @@ define archhelp
   echo  '		   (your) ~/bin/installkernel or'
   echo  '		   (distribution) /sbin/installkernel or'
   echo  '		   install to $$(INSTALL_PATH) and run lilo'
+  echo  '  bzdisk       - Create a boot floppy in /dev/fd0'
+  echo  '  fdimage      - Create a boot floppy image'
 endef
 
+CLEAN_FILES += arch/$(ARCH)/boot/fdimage arch/$(ARCH)/boot/mtools.conf

arch/i386/boot/Makefile

@@ -62,8 +62,36 @@ $(obj)/compressed/vmlinux: FORCE
 	$(Q)$(MAKE) -f scripts/Makefile.build obj=$(obj)/compressed \
 					IMAGE_OFFSET=$(IMAGE_OFFSET) $@
 
-zdisk: $(BOOTIMAGE)
-	dd bs=8192 if=$(BOOTIMAGE) of=/dev/fd0
+# Set this if you want to pass append arguments to the zdisk/fdimage kernel
+FDARGS = 
+
+$(obj)/mtools.conf: $(obj)/mtools.conf.in
+	sed -e 's|@OBJ@|$(obj)|g' < $< > $@
+
+# This requires write access to /dev/fd0
+zdisk: $(BOOTIMAGE) $(obj)/mtools.conf
+	MTOOLSRC=$(src)/mtools.conf mformat a:			; sync
+	syslinux /dev/fd0					; sync
+	echo 'default linux $(FDARGS)' | \
+		MTOOLSRC=$(src)/mtools.conf mcopy - a:syslinux.cfg
+	MTOOLSRC=$(src)/mtools.conf mcopy $(BOOTIMAGE) a:linux	; sync
+
+# These require being root or having syslinux 2.02 or higher installed
+fdimage fdimage144: $(BOOTIMAGE) $(src)/mtools.conf
+	dd if=/dev/zero of=$(obj)/fdimage bs=1024 count=1440
+	MTOOLSRC=$(src)/mtools.conf mformat v:			; sync
+	syslinux $(obj)/fdimage					; sync
+	echo 'default linux $(FDARGS)' | \
+		MTOOLSRC=$(src)/mtools.conf mcopy - v:syslinux.cfg
+	MTOOLSRC=$(src)/mtools.conf mcopy $(BOOTIMAGE) v:linux	; sync
+
+fdimage288: $(BOOTIMAGE) $(src)/mtools.conf
+	dd if=/dev/zero of=$(obj)/fdimage bs=1024 count=2880
+	MTOOLSRC=$(src)/mtools.conf mformat w:			; sync
+	syslinux $(obj)/fdimage					; sync
+	echo 'default linux $(FDARGS)' | \
+		MTOOLSRC=$(src)/mtools.conf mcopy - w:syslinux.cfg
+	MTOOLSRC=$(src)/mtools.conf mcopy $(BOOTIMAGE) w:linux	; sync
 
 zlilo: $(BOOTIMAGE)
 	if [ -f $(INSTALL_PATH)/vmlinuz ]; then mv $(INSTALL_PATH)/vmlinuz $(INSTALL_PATH)/vmlinuz.old; fi

arch/i386/boot/mtools.conf.in

+#
+# mtools configuration file for "make (b)zdisk"
+#
+
+# Actual floppy drive
+drive a:
+  file="/dev/fd0"
+
+# 1.44 MB floppy disk image
+drive v:
+  file="@OBJ@/fdimage" cylinders=80 heads=2 sectors=18 filter
+
+# 2.88 MB floppy disk image (mostly for virtual uses)
+drive w:
+  file="@OBJ@/fdimage" cylinders=80 heads=2 sectors=36 filter
+
+

arch/i386/boot/tools/build.c

@@ -150,13 +150,10 @@ int main(int argc, char ** argv)
 	sz = sb.st_size;
 	fprintf (stderr, "System is %d kB\n", sz/1024);
 	sys_size = (sz + 15) / 16;
-	/* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */
-	if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE))
+	/* 0x40000*16 = 4.0 MB, reasonable estimate for the current maximum */
+	if (sys_size > (is_big_kernel ? 0x40000 : DEF_SYSSIZE))
 		die("System is too big. Try using %smodules.",
 			is_big_kernel ? "" : "bzImage or ");
-	if (sys_size > 0xefff)
-		fprintf(stderr,"warning: kernel is too big for standalone boot "
-		    "from floppy\n");
 	while (sz > 0) {
 		int l, n;
 

arch/x86_64/boot/Makefile

@@ -73,7 +73,7 @@ zdisk: $(BOOTIMAGE) $(obj)/mtools.conf
 		MTOOLSRC=$(src)/mtools.conf mcopy - a:syslinux.cfg
 	MTOOLSRC=$(src)/mtools.conf mcopy $(BOOTIMAGE) a:linux	; sync
 
-# These require being root or having syslinux run setuid
+# These require being root or having syslinux 2.02 or higher installed
 fdimage fdimage144: $(BOOTIMAGE) $(src)/mtools.conf
 	dd if=/dev/zero of=$(obj)/fdimage bs=1024 count=1440
 	MTOOLSRC=$(src)/mtools.conf mformat v:			; sync