MIPS: Cleanup and Fixup of compressed kernel support

 o Remove the .initrd section.  The initrd section was already handled
   when vmlinux was linked.
 o Discard .MIPS.options, .options, .pdr, .reginfo, .comment and .note
   sections.  If .MIPS.options is not removed, kernels compiled with gcc
   3.4.6 will not boot.
 o Clean up the file format.
 o Remove several other unneeded sections.

Tested with GCC 3.4.6 and 4.4.1 with and without initrd.
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/785/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/boot/compressed/Makefile

@@ -56,7 +56,7 @@ $(obj)/piggy.o: $(obj)/vmlinux.$(suffix_y) $(obj)/dummy.o
 LDFLAGS_vmlinuz := $(LDFLAGS) -Ttext $(VMLINUZ_LOAD_ADDRESS) -T
 vmlinuz: $(src)/ld.script $(obj-y) $(obj)/piggy.o
 	$(call if_changed,ld)
-	$(Q)$(OBJCOPY) $(OBJCOPYFLAGS) -R .comment -R .stab -R .stabstr -R .initrd -R .sysmap $@
+	$(Q)$(OBJCOPY) $(OBJCOPYFLAGS) $@
 
 #
 # Some DECstations need all possible sections of an ECOFF executable
@@ -84,14 +84,11 @@ vmlinuz.ecoff: $(obj)/../elf2ecoff $(VMLINUZ)
 $(obj)/../elf2ecoff: $(src)/../elf2ecoff.c
 	$(Q)$(HOSTCC) -o $@ $^
 
-drop-sections	= .reginfo .mdebug .comment .note .pdr .options .MIPS.options
-strip-flags	= $(addprefix --remove-section=,$(drop-sections))
-
-OBJCOPYFLAGS_vmlinuz.bin := $(OBJCOPYFLAGS) -O binary $(strip-flags)
+OBJCOPYFLAGS_vmlinuz.bin := $(OBJCOPYFLAGS) -O binary
 vmlinuz.bin: vmlinuz
 	$(call if_changed,objcopy)
 
-OBJCOPYFLAGS_vmlinuz.srec := $(OBJCOPYFLAGS) -S -O srec $(strip-flags)
+OBJCOPYFLAGS_vmlinuz.srec := $(OBJCOPYFLAGS) -S -O srec
 vmlinuz.srec: vmlinuz
 	$(call if_changed,objcopy)
 

arch/mips/boot/compressed/decompress.c

@@ -28,8 +28,6 @@ char *zimage_start;
 
 /* The linker tells us where the image is. */
 extern unsigned char __image_begin, __image_end;
-extern unsigned char __ramdisk_begin, __ramdisk_end;
-unsigned long initrd_size;
 
 /* debug interfaces  */
 extern void puts(const char *s);
@@ -102,14 +100,6 @@ void decompress_kernel(unsigned long boot_heap_start)
 	puthex((unsigned long)(zimage_size + zimage_start));
 	puts("\n");
 
-	if (initrd_size) {
-		puts("initrd at:     ");
-		puthex((unsigned long)(&__ramdisk_begin));
-		puts(" ");
-		puthex((unsigned long)(&__ramdisk_end));
-		puts("\n");
-	}
-
 	/* this area are prepared for mallocing when decompressing */
 	free_mem_ptr = boot_heap_start;
 	free_mem_end_ptr = boot_heap_start + BOOT_HEAP_SIZE;

arch/mips/boot/compressed/ld.script

+/*
+ * ld.script for compressed kernel support of MIPS
+ *
+ * Copyright (C) 2009 Lemote Inc.
+ * Author: Wu Zhangjin <wuzj@lemote.com>
+ */
+
 OUTPUT_ARCH(mips)
 ENTRY(start)
 SECTIONS
 {
-  /* Read-only sections, merged into text segment: */
-  .init          : { *(.init)		} =0
-  .text      :
-  {
-    _ftext = . ;
-    *(.text)
-    *(.rodata)
-    *(.rodata1)
-    /* .gnu.warning sections are handled specially by elf32.em.  */
-    *(.gnu.warning)
-  } =0
-  .kstrtab : { *(.kstrtab) }
-
-  . = ALIGN(16);		/* Exception table */
-  __start___ex_table = .;
-  __ex_table : { *(__ex_table) }
-  __stop___ex_table = .;
-
-  __start___dbe_table = .;	/* Exception table for data bus errors */
-  __dbe_table : { *(__dbe_table) }
-  __stop___dbe_table = .;
-
-  __start___ksymtab = .;	/* Kernel symbol table */
-  __ksymtab : { *(__ksymtab) }
-  __stop___ksymtab = .;
-
-  _etext = .;
-
-  . = ALIGN(8192);
-  .data.init_task : { *(.data.init_task) }
-
-  /* Startup code */
-  . = ALIGN(4096);
-  __init_begin = .;
-  .text.init : { *(.text.init) }
-  .data.init : { *(.data.init) }
-  . = ALIGN(16);
-  __setup_start = .;
-  .setup.init : { *(.setup.init) }
-  __setup_end = .;
-  __initcall_start = .;
-  .initcall.init : { *(.initcall.init) }
-  __initcall_end = .;
-  . = ALIGN(4096);	/* Align double page for init_task_union */
-  __init_end = .;
-
-  . = ALIGN(4096);
-  .data.page_aligned : { *(.data.idt) }
-
-  . = ALIGN(32);
-  .data.cacheline_aligned : { *(.data.cacheline_aligned) }
+	/* . = VMLINUZ_LOAD_ADDRESS */
+	/* read-only */
+	_text = .;	/* Text and read-only data */
+	.text	: {
+		_ftext = . ;
+		*(.text)
+		*(.rodata)
+	} = 0
+	_etext = .;	/* End of text section */
 
-  .fini      : { *(.fini)    } =0
-  .reginfo : { *(.reginfo) }
-  /* Adjust the address for the data segment.  We want to adjust up to
-     the same address within the page on the next page up.  It would
-     be more correct to do this:
-       . = .;
-     The current expression does not correctly handle the case of a
-     text segment ending precisely at the end of a page; it causes the
-     data segment to skip a page.  The above expression does not have
-     this problem, but it will currently (2/95) cause BFD to allocate
-     a single segment, combining both text and data, for this case.
-     This will prevent the text segment from being shared among
-     multiple executions of the program; I think that is more
-     important than losing a page of the virtual address space (note
-     that no actual memory is lost; the page which is skipped can not
-     be referenced).  */
-  . = .;
-  .data    :
-  {
-    _fdata = . ;
-    *(.data)
+	/* writable */
+	.data	: {	/* Data */
+		_fdata = . ;
+		*(.data)
+		/* Put the compressed image here, so bss is on the end. */
+		__image_begin = .;
+		*(.image)
+		__image_end = .;
+		CONSTRUCTORS
+	}
+	.sdata	: { *(.sdata) }
+	. = ALIGN(4);
+	_edata  =  .;	/* End of data section */
 
-   /* Put the compressed image here, so bss is on the end. */
-   __image_begin = .;
-   *(.image)
-   __image_end = .;
-   /* Align the initial ramdisk image (INITRD) on page boundaries. */
-   . = ALIGN(4096);
-   __ramdisk_begin = .;
-   *(.initrd)
-   __ramdisk_end = .;
-   . = ALIGN(4096);
+	/* BSS */
+	__bss_start = .;
+	_fbss = .;
+	.sbss	: { *(.sbss) *(.scommon) }
+	.bss	: {
+		*(.dynbss)
+		*(.bss)
+		*(COMMON)
+	}
+	.  = ALIGN(4);
+	_end = . ;
 
-    CONSTRUCTORS
-  }
-  .data1   : { *(.data1) }
-  _gp = . + 0x8000;
-  .lit8 : { *(.lit8) }
-  .lit4 : { *(.lit4) }
-  .ctors         : { *(.ctors)   }
-  .dtors         : { *(.dtors)   }
-  .got           : { *(.got.plt) *(.got) }
-  .dynamic       : { *(.dynamic) }
-  /* We want the small data sections together, so single-instruction offsets
-     can access them all, and initialized data all before uninitialized, so
-     we can shorten the on-disk segment size.  */
-  .sdata     : { *(.sdata) }
-  . = ALIGN(4);
-  _edata  =  .;
-  PROVIDE (edata = .);
+	/* These are needed for ELF backends which have not yet been converted
+	 * to the new style linker.  */
 
-  __bss_start = .;
-  _fbss = .;
-  .sbss      : { *(.sbss) *(.scommon) }
-  .bss       :
-  {
-   *(.dynbss)
-   *(.bss)
-   *(COMMON)
-   .  = ALIGN(4);
-  _end = . ;
-  PROVIDE (end = .);
-  }
+	.stab 0 : { *(.stab) }
+	.stabstr 0 : { *(.stabstr) }
 
-  /* Sections to be discarded */
-  /DISCARD/ :
-  {
-        *(.text.exit)
-        *(.data.exit)
-        *(.exitcall.exit)
-  }
+	/* These must appear regardless of  .  */
+	.gptab.sdata : { *(.gptab.data) *(.gptab.sdata) }
+	.gptab.sbss : { *(.gptab.bss) *(.gptab.sbss) }
 
-  /* This is the MIPS specific mdebug section.  */
-  .mdebug : { *(.mdebug) }
-  /* These are needed for ELF backends which have not yet been
-     converted to the new style linker.  */
-  .stab 0 : { *(.stab) }
-  .stabstr 0 : { *(.stabstr) }
-  /* DWARF debug sections.
-     Symbols in the .debug DWARF section are relative to the beginning of the
-     section so we begin .debug at 0.  It's not clear yet what needs to happen
-     for the others.   */
-  .debug          0 : { *(.debug) }
-  .debug_srcinfo  0 : { *(.debug_srcinfo) }
-  .debug_aranges  0 : { *(.debug_aranges) }
-  .debug_pubnames 0 : { *(.debug_pubnames) }
-  .debug_sfnames  0 : { *(.debug_sfnames) }
-  .line           0 : { *(.line) }
-  /* These must appear regardless of  .  */
-  .gptab.sdata : { *(.gptab.data) *(.gptab.sdata) }
-  .gptab.sbss : { *(.gptab.bss) *(.gptab.sbss) }
-  .comment : { *(.comment) }
-  .note : { *(.note) }
+	/* Sections to be discarded */
+	/DISCARD/	: {
+		*(.MIPS.options)
+		*(.options)
+		*(.pdr)
+		*(.reginfo)
+		*(.comment)
+		*(.note)
+	}
 }