Thread: [linuxsh-dev] Re: [linux-sh:01233] Re: ROMable image

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>>>>> "Jesper" == Jesper Skov <js...@re...> writes:

>>>>> "Manoj" == Manoj Kumar <man...@so...> writes:
Manoj> Hello all, I want to build a ROMable kernel image.I am using
Manoj> NIIBE's sh-linux 2.4.0.  I am not using a CE device.  Does
Manoj> anyone know about a patch for doing the same?

Manoj> I found a patch in Ludovic's site,but it is for linux2.3.23.

Jesper> I have some XIP patches. I need to clean them up and submit
Jesper> them. Hopefully today, but I need to check that they are OK to
Jesper> publicize - so no guarantees.

I have now uploaded the simple patch below to the patch manager at
sourceforge.

The only real problem with the patch as far as I'm concerned is that
it uses a hack to separate arguments from the empty_zero_page. I had
to do this because (a) I'm using some scripts to write boot parameters
into the start of the boot image and (b) empty_zero_page has to be in
the data section so it will end up in RAM.

I don't know if the patch is worth integrating the public tree before
that issue has been fixed. But even so, there are a few generic fixes
in there as well: Documentation fix + lose module exit functions.

For debugging with the XIP configuration, I configure something like
this (I have 8MB RAM @ 0x0c000000):

 CONFIG_SH_XIP=y
 CONFIG_XIP_ROM_START=0C100000
 CONFIG_MEMORY_START=0C300000
 CONFIG_MEMORY_SIZE=00500000

Thus leaving 2MB @ 0x0c100000 for the boot image (kernel text +
initrd). On startup the data section is copied to MEMORY_START and the
5MB @ 0x0c300000 is mapped as if it was the only RAM in the
system. Then I'm free to still use breakpoints/single-step the kernel
text.

For production I put CONFIG_XIP_ROM_START=00100000, and have the full
8MB of RAM for the system. (the 1MB missing are for the boot monitor).


Cheers,
Jesper


	2000-08-25  Jesper Skov  <js...@re...>

	* arch/sh/Makefile: Select linker script based on XIP config.
	* arch/sh/config.in: Added XIP related and memory default size
	options.
	* arch/sh/vmlinux.lds.S: Added _sdata label. Discard .exitcalls
	from modules.
	* arch/sh/vmlinux.lds.xip.S: [Added] Linker script for XIP
	configuration.
	* arch/sh/kernel/head.S: Copy data to RAM in XIP config. Crufty
	hack to keep arguments at front of image while empty_zero_page ends
	up in RAM.
	* arch/sh/kernel/setup.c (parse_cmdline): Use configurable default
	memory size. empty_zero_page/argument_page XIP hack.
	* arch/sh/mm/init.c (mem_init): Use _sdata instead of _etext for
	size calculation.
	* Documentation/Configure.help: Added descriptions for new
	options. Fixed CPU selection description.
	



Index: Documentation/Configure.help
===================================================================
RCS file: /cvsroot/linuxsh/kernel/Documentation/Configure.help,v
retrieving revision 1.21
diff -u -5 -r1.21 Configure.help

--- Documentation/Configure.help	2000/08/10 01:19:39	1.21
+++ Documentation/Configure.help	2000/08/25 08:48:00
@@ -14818,14 +14818,15 @@
 
 # The following options are for Linux when running on the Hitachi
 # SuperH family of RISC microprocessors.
 
 CPU Selection
-CONFIG_CPU_SUBTYPE_SH7708
+CONFIG_CPU_SUBTYPE_SH7707
   This is the type of your Hitachi SuperH processor. This information is
   used for optimizing and configuration purposes.
 
+  - "SH7707" for SH7707
   - "SH7708" for SH7708, SH7708S, SH7708R
   - "SH7709" for SH7707, SH7709, SH7709A, and SH7729.
   - "SH7750" for SH7750, and possibly SH7751
 
 Physical memory start address
@@ -14837,10 +14838,40 @@
 
   You should set this value to the address of the lowest
   RAM location.
 
   A value of 0c000000 will work for most boards.
+
+Execute-in-place kernel
+CONFIG_SH_XIP
+  Selecting this option (eXecute-In-Place) will allow the kernel text
+  and rodata segments to remain in flash/ROM memory, saving on RAM usage.
+
+  There might be a small performance degradation due to the flash/ROM
+  being slower than DRAM, but since the kernel only uses a fraction of
+  the total CPU time, this should not be a problem. The RAM freed up
+  by running the kernel out of flash/ROM will probably more than
+  counter this slowdown.
+
+XIP text segment start address
+CONFIG_XIP_ROM_START
+  When the XIP option is selected, this option controls where the
+  kernel text segment starts. SuperH processors always have flash/ROM
+  at address zero, but there may be reasons to put the kernel
+  elsewhere:
+
+  Higher up in the flash/ROM, leaving the start of the flash/ROM to a
+  boot monitor which can start Linux.
+
+  In RAM, allowing for debugging. In this case you should adjust the
+  CONFIG_MEMORY_START option as well, leaving a gap for the kernel in
+  RAM.
+
+Memory size
+CONFIG_MEMORY_SIZE
+  The amount of RAM used by Linux can be controlled with a kernel
+  parameter, but this option allows for a configurable default.
 
 Directly Connected Compact Flash support
 CONFIG_CF_ENABLER
   If your board has "Directly Connected" Compact Flash at area 6, 
   you may want to enable this option.  Then, you can use CF as
Index: arch/sh/Makefile
===================================================================
RCS file: /cvsroot/linuxsh/kernel/arch/sh/Makefile,v
retrieving revision 1.9
diff -u -5 -r1.9 Makefile
--- arch/sh/Makefile	2000/07/31 12:35:55	1.9
+++ arch/sh/Makefile	2000/08/25 08:48:01
@@ -80,14 +80,20 @@
 SUBDIRS += arch/sh/overdrive
 CORE_FILES += arch/sh/overdrive/overdrive.o
 endif
 endif
 
+ifdef CONFIG_SH_XIP
+LINKSCRIPT_SRC = arch/sh/vmlinux.lds.xip.S
+else
+LINKSCRIPT_SRC = arch/sh/vmlinux.lds.S
+endif
+
 vmlinux: arch/sh/vmlinux.lds
 
-arch/sh/vmlinux.lds: arch/sh/vmlinux.lds.S FORCE
-	$(CPP) -C -P -I$(HPATH) -Ush arch/sh/vmlinux.lds.S >arch/sh/vmlinux.lds
+arch/sh/vmlinux.lds: $(LINKSCRIPT_SRC) FORCE
+	$(CPP) -C -P -I$(HPATH) -Ush $(LINKSCRIPT_SRC) >arch/sh/vmlinux.lds
 
 FORCE: ;
 
 zImage: vmlinux
 	@$(MAKEBOOT) zImage
Index: arch/sh/config.in
===================================================================
RCS file: /cvsroot/linuxsh/kernel/arch/sh/config.in,v
retrieving revision 1.19
diff -u -5 -r1.19 config.in
--- arch/sh/config.in	2000/08/05 07:04:45	1.19
+++ arch/sh/config.in	2000/08/25 08:48:02
@@ -52,16 +52,21 @@
 if [ "$CONFIG_CPU_SUBTYPE_SH7750" = "y" ]; then
    define_bool CONFIG_CPU_SH3 n
    define_bool CONFIG_CPU_SH4 y
 fi
 bool 'Little Endian' CONFIG_CPU_LITTLE_ENDIAN
+bool 'Kernel XIP' CONFIG_SH_XIP
+if [ "$CONFIG_SH_XIP" = "y" ]; then
+    hex 'ROM physical start address' CONFIG_XIP_ROM_START 08100000
+fi
 if [ "$CONFIG_SH_SOLUTION_ENGINE" = "y" -o "$CONFIG_SH_HP600" = "y" -o \
      "$CONFIG_SH_OVERDRIVE" = "y" ]; then
   define_hex CONFIG_MEMORY_START 0c000000
 else
   hex 'Physical memory start address' CONFIG_MEMORY_START 08000000
 fi
+hex 'Memory size' CONFIG_MEMORY_SIZE 00400000
 endmenu
 
 mainmenu_option next_comment
 comment 'General setup'
 
Index: arch/sh/vmlinux.lds.S
===================================================================
RCS file: /cvsroot/linuxsh/kernel/arch/sh/vmlinux.lds.S,v
retrieving revision 1.6
diff -u -5 -r1.6 vmlinux.lds.S
--- arch/sh/vmlinux.lds.S	2000/08/05 06:25:22	1.6
+++ arch/sh/vmlinux.lds.S	2000/08/25 08:48:02
@@ -35,10 +35,11 @@
   __start___ksymtab = .;	/* Kernel symbol table */
   __ksymtab : { *(__ksymtab) }
   __stop___ksymtab = .;
 
   _etext = .;			/* End of text section */
+  _sdata = .;			/* Start of data section */
 
   .data : {			/* Data */
 	*(.data)
 	CONSTRUCTORS
 	}
@@ -87,10 +88,11 @@
    * it's a module.
    */
   /DISCARD/ : {
 	*(.text.exit)
 	*(.data.exit)
+	*(.exitcall.*)
 	}
 
   /* Stabs debugging sections.  */
   .stab 0 : { *(.stab) }
   .stabstr 0 : { *(.stabstr) }
Index: arch/sh/vmlinux.lds.xip.S
===================================================================
RCS file: vmlinux.lds.xip.S
diff -N vmlinux.lds.xip.S
--- arch/sh/vmlinux.lds.xip.S	Tue May  5 13:32:27 1998
+++ arch/sh/vmlinux.lds.xip.S	Fri Aug 25 01:48:03 2000
@@ -0,0 +1,155 @@
+/* $Id: vmlinux.lds.xip.S,v 1.3 2000/08/21 14:12:02 jskov Exp $
+ * ld script to make SuperH Linux kernel
+ * Written by Niibe Yutaka
+ */
+
+#include <linux/config.h>
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+OUTPUT_FORMAT("elf32-shl", "elf32-shl", "elf32-shl")
+#else
+OUTPUT_FORMAT("elf32-sh", "elf32-sh", "elf32-sh")
+#endif
+OUTPUT_ARCH(sh)
+ENTRY(_start)
+
+#define ALIGN_LMA 4
+#define ALIGNED_GAP(_section_, _align_) (((ADDR(_section_)+SIZEOF(_section_)+(_align_)-1) & ~((_align_)-1))-ADDR(_section_))
+#define FOLLOWING(_section_, _align_) AT (LOADADDR (_section_) + ALIGNED_GAP(_section_, _align_))
+
+SECTIONS
+{
+  . = 0x80000000 + CONFIG_XIP_ROM_START + 0x1000;
+  _text = .;			/* Text and read-only data */
+  text = .;			/* Text and read-only data */
+  .argument_page : {
+	*(.argument_page)
+	} = 0
+  .text : {
+	*(.text)
+	*(.fixup)
+	*(.gnu.warning)
+	*(.text.init)
+	} = 0x0009
+  .text.lock : { *(.text.lock) }	/* out-of-line lock text */
+  .rodata : { *(.rodata) }
+  .kstrtab : { *(.kstrtab) }
+
+  . = ALIGN(16);		/* Exception table */
+  __start___ex_table = .;
+  __ex_table : { *(__ex_table) }
+  __stop___ex_table = .;
+
+  __start___ksymtab = .;	/* Kernel symbol table */
+  __ksymtab : { *(__ksymtab) }
+  __stop___ksymtab = .;
+
+  _etext = .;			/* End of text section */
+
+  _xip_load = .;		/* Load address of data for RAM */
+  . = 0x80000000 + CONFIG_MEMORY_START;
+  _xip_sdata = .;		/* Start of data section */
+  _sdata = .;			/* Start of data section */
+  .empty_zero_page : FOLLOWING(__ksymtab, 1) {
+	*(.empty_zero_page)
+	} = 0
+  . = ALIGN(4096);
+  .data : FOLLOWING(.empty_zero_page, 4096) {/* Data */
+	*(.data)
+#if 0
+	CONSTRUCTORS
+#endif
+	}
+
+  _edata = .;			/* End of data section */
+
+  . = ALIGN(8192);		/* init_task */
+  .data.init_task : FOLLOWING(.data, 8192) { *(.data.init_task) }
+  /* stack */
+  .stack : { stack = .;  _stack = .; }
+
+  . = ALIGN(4096);		/* Init code and data */
+  __init_begin = .;
+  .data.init : FOLLOWING(.data.init_task, 4096) { *(.data.init) }
+  . = ALIGN(16);
+  __setup_start = .;
+  .setup.init : FOLLOWING(.data.init, 16) { *(.setup.init) }
+  __setup_end = .;
+  __initcall_start = .;
+  .initcall.init : FOLLOWING(.setup.init, 1) { *(.initcall.init) }
+  __initcall_end = .;
+  __machvec_start = .;
+  .machvec.init : FOLLOWING(.initcall.init, 1) { *(.machvec.init) }
+  __machvec_end = .;
+  . = ALIGN(4096);
+  __init_end = .;
+
+#if 0
+  . = ALIGN(4096);
+  .data.page_aligned : FOLLOWING(.setup.init, 4096) { *(.data.idt) }
+#endif
+
+#if 0
+  . = ALIGN(32);
+  .data.cacheline_aligned : FOLLOWING(.data.page_aligned, 32) { *(.data.cacheline_aligned) }
+#else
+  . = ALIGN(4096);
+  .data.cacheline_aligned : FOLLOWING(.initcall.init, 4096) { *(.data.cacheline_aligned) }
+#endif
+
+  . = ALIGN(4);
+
+  _xip_edata = .;		/* End of data that needs to be copied */
+
+  __bss_start = .;		/* BSS */
+  .bss : {
+	*(.bss)
+	}
+  . = ALIGN(4);
+  _end = . ;
+
+  /* When something in the kernel is NOT compiled as a module, the
+   * module cleanup code and data are put into these segments.  Both
+   * can then be thrown away, as cleanup code is never called unless
+   * it's a module.
+   */
+  /DISCARD/ : {
+	*(.text.exit)
+	*(.data.exit)
+	*(.exitcall.*)
+	}
+
+  /* Stabs debugging sections.  */
+  .stab 0 : { *(.stab) }
+  .stabstr 0 : { *(.stabstr) }
+  .stab.excl 0 : { *(.stab.excl) }
+  .stab.exclstr 0 : { *(.stab.exclstr) }
+  .stab.index 0 : { *(.stab.index) }
+  .stab.indexstr 0 : { *(.stab.indexstr) }
+  .comment 0 : { *(.comment) }
+  /* DWARF debug sections.
+     Symbols in the DWARF debugging section are relative to the beginning
+     of the section so we begin .debug at 0.  */
+  /* DWARF 1 */
+  .debug          0 : { *(.debug) }
+  .line           0 : { *(.line) }
+  /* GNU DWARF 1 extensions */
+  .debug_srcinfo  0 : { *(.debug_srcinfo) }
+  .debug_sfnames  0 : { *(.debug_sfnames) }
+  /* DWARF 1.1 and DWARF 2 */
+  .debug_aranges  0 : { *(.debug_aranges) }
+  .debug_pubnames 0 : { *(.debug_pubnames) }
+  /* DWARF 2 */
+  .debug_info     0 : { *(.debug_info) }
+  .debug_abbrev   0 : { *(.debug_abbrev) }
+  .debug_line     0 : { *(.debug_line) }
+  .debug_frame    0 : { *(.debug_frame) }
+  .debug_str      0 : { *(.debug_str) }
+  .debug_loc      0 : { *(.debug_loc) }
+  .debug_macinfo  0 : { *(.debug_macinfo) }
+  /* SGI/MIPS DWARF 2 extensions */
+  .debug_weaknames 0 : { *(.debug_weaknames) }
+  .debug_funcnames 0 : { *(.debug_funcnames) }
+  .debug_typenames 0 : { *(.debug_typenames) }
+  .debug_varnames  0 : { *(.debug_varnames) }
+  /* These must appear regardless of  .  */
+}
Index: arch/sh/kernel/head.S
===================================================================
RCS file: /cvsroot/linuxsh/kernel/arch/sh/kernel/head.S,v
retrieving revision 1.7
diff -u -5 -r1.7 head.S
--- arch/sh/kernel/head.S	2000/07/04 06:24:39	1.7
+++ arch/sh/kernel/head.S	2000/08/25 08:48:03
@@ -10,12 +10,21 @@
  *
  * Head.S contains the SH exception handlers and startup code.
  */
 #include <linux/linkage.h>
 
+#ifdef CONFIG_SH_XIP
 	.section	.empty_zero_page, "aw"
 ENTRY(empty_zero_page)
+	.long	0
+
+	.section	.argument_page, "aw"
+ENTRY(argument_page)
+#else
+	.section	.empty_zero_page, "aw"
+ENTRY(empty_zero_page)
+#endif
 	.long	1		/* MOUNT_ROOT_RDONLY */
 	.long	0		/* RAMDISK_FLAGS */
 	.long	0x0200		/* ORIG_ROOT_DEV */
 	.long	1		/* LOADER_TYPE */
 	.long	0x00360000	/* INITRD_START */
@@ -58,10 +67,21 @@
 #endif
 	!			Enable cache
 	mov.l	6f, $r0
 	jsr	@$r0
 	 nop
+#ifdef CONFIG_SH_XIP
+	!			Copy data to RAM
+        mov.l   10f,$r0
+        mov.l   11f,$r1
+        mov.l   12f,$r2
+9:      mov.l   @$r0+,$r3               ! get word from ROM
+        mov.l   $r3,@$r1                ! store in RAM
+        add     #4,$r1
+        cmp/eq  $r1,$r2                 ! compare
+        bf      9b                      ! loop if not yet done
+#endif
 	!			Clear BSS area
 	mov.l	3f, $r1
 	add	#4, $r1
 	mov.l	4f, $r2
 	mov	#0, $r0
@@ -80,6 +100,11 @@
 4:	.long	SYMBOL_NAME(_end)
 5:	.long	SYMBOL_NAME(start_kernel)
 6:	.long	SYMBOL_NAME(cache_init)
 #if defined(__SH4__)
 7:	.long   SYMBOL_NAME(fpu_init)
+#endif
+#ifdef CONFIG_SH_XIP
+10:	.long	SYMBOL_NAME(_xip_load)
+11:	.long	SYMBOL_NAME(_xip_sdata)
+12:	.long	SYMBOL_NAME(_xip_edata)
 #endif
Index: arch/sh/kernel/setup.c
===================================================================
RCS file: /cvsroot/linuxsh/kernel/arch/sh/kernel/setup.c,v
retrieving revision 1.11
diff -u -5 -r1.11 setup.c
--- arch/sh/kernel/setup.c	2000/08/05 06:25:23	1.11
+++ arch/sh/kernel/setup.c	2000/08/25 08:48:04
@@ -69,11 +69,16 @@
 static struct sh_machine_vector* __init get_mv_byname(const char* name);
 
 /*
  * This is set up by the setup-routine at boot-time
  */
+#ifndef CONFIG_SH_XIP
 #define PARAM	((unsigned char *)empty_zero_page)
+#else
+extern unsigned char argument_page;
+#define PARAM	((unsigned char *)&argument_page)
+#endif
 
 #define MOUNT_ROOT_RDONLY (*(unsigned long *) (PARAM+0x000))
 #define RAMDISK_FLAGS (*(unsigned long *) (PARAM+0x004))
 #define ORIG_ROOT_DEV (*(unsigned long *) (PARAM+0x008))
 #define LOADER_TYPE (*(unsigned long *) (PARAM+0x00c))
@@ -202,12 +207,12 @@
 	/* Save unparsed command line copy for /proc/cmdline */
 	memcpy(saved_command_line, COMMAND_LINE, COMMAND_LINE_SIZE);
 	saved_command_line[COMMAND_LINE_SIZE-1] = '\0';
 
 	memory_start = (unsigned long)PAGE_OFFSET+__MEMORY_START;
-	/* Default is 4Mbyte. */
-	memory_end = (unsigned long)PAGE_OFFSET+0x00400000+__MEMORY_START;
+	/* Default is specified by the configuration */
+	memory_end = (unsigned long)PAGE_OFFSET+CONFIG_MEMORY_SIZE+__MEMORY_START;
 
 	for (;;) {
 		/*
 		 * "mem=XXX[kKmM]" defines a size of memory.
 		 */
Index: arch/sh/mm/init.c
===================================================================
RCS file: /cvsroot/linuxsh/kernel/arch/sh/mm/init.c,v
retrieving revision 1.6
diff -u -5 -r1.6 init.c
--- arch/sh/mm/init.c	2000/08/16 08:34:04	1.6
+++ arch/sh/mm/init.c	2000/08/25 08:48:04
@@ -176,11 +176,11 @@
 	show_buffers();
 }
 
 /* References to section boundaries */
 
-extern char _text, _etext, _edata, __bss_start, _end;
+extern char _text, _etext, _sdata, _edata, __bss_start, _end;
 extern char __init_begin, __init_end;
 
 pgd_t swapper_pg_dir[1024];
 
 /* It'd be good if these lines were in the standard header file. */
@@ -251,11 +251,11 @@
 		 * Only count reserved RAM pages
 		 */
 		if (PageReserved(mem_map+tmp))
 			reservedpages++;
 	codesize =  (unsigned long) &_etext - (unsigned long) &_text;
-	datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
+	datasize =  (unsigned long) &_edata - (unsigned long) &_sdata;
 	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 
 	printk("Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init)\n",
 		(unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
 		max_mapnr << (PAGE_SHIFT-10),

