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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ppc/boot/common/crt0.S
downloadlinux-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz
linux-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/* Copyright (c) 1997 Paul Mackerras <paulus@cs.anu.edu.au>
+ * Initial Power Macintosh COFF version.
+ * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
+ * Modifications for IBM PowerPC 400-class processor evaluation
+ * boards.
+ *
+ * Module name: crt0.S
+ *
+ * Description:
+ * Boot loader execution entry point. Clears out .bss section as per
+ * ANSI C requirements. Invalidates and flushes the caches over the
+ * range covered by the boot loader's .text section. Sets up a stack
+ * below the .text section entry point.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <asm/ppc_asm.h>
+
+ .text
+
+ .globl _start
+_start:
+#ifdef XCOFF
+ .long __start,0,0
+
+ .globl __start
+__start:
+#endif
+
+ ## Flush and invalidate the caches for the range in memory covering
+ ## the .text section of the boot loader
+
+ lis r9,_start@h # r9 = &_start
+ lis r8,_etext@ha #
+ addi r8,r8,_etext@l # r8 = &_etext
+3: dcbf r0,r9 # Flush the data cache
+ icbi r0,r9 # Invalidate the instruction cache
+ addi r9,r9,0x10 # Increment by one cache line
+ cmplw cr0,r9,r8 # Are we at the end yet?
+ blt 3b # No, keep flushing and invalidating
+ sync # sync ; isync after flushing the icache
+ isync
+
+ ## Clear out the BSS as per ANSI C requirements
+
+ lis r7,_end@ha
+ addi r7,r7,_end@l # r7 = &_end
+ lis r8,__bss_start@ha #
+ addi r8,r8,__bss_start@l # r8 = &_bss_start
+
+ ## Determine how large an area, in number of words, to clear
+
+ subf r7,r8,r7 # r7 = &_end - &_bss_start + 1
+ addi r7,r7,3 # r7 += 3
+ srwi. r7,r7,2 # r7 = size in words.
+ beq 2f # If the size is zero, do not bother
+ addi r8,r8,-4 # r8 -= 4
+ mtctr r7 # SPRN_CTR = number of words to clear
+ li r0,0 # r0 = 0
+1: stwu r0,4(r8) # Clear out a word
+ bdnz 1b # If we are not done yet, keep clearing
+2:
+
+#ifdef CONFIG_40x
+ ## Set up the stack
+
+ lis r9,_start@h # r9 = &_start (text section entry)
+ ori r9,r9,_start@l
+ subi r1,r9,64 # Start the stack 64 bytes below _start
+ clrrwi r1,r1,4 # Make sure it is aligned on 16 bytes.
+ li r0,0
+ stwu r0,-16(r1)
+ mtlr r9
+#endif
+
+ b start # All done, start the real work.