Add i486 toolchain support

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3349 42af7a65-404d-4744-a932-0658087f49c3

Documentation/NuttX.html

@@ -2159,6 +2159,16 @@ pascal-2.1 2011-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
 
 buildroot-1.10 2011-xx-xx <spudmonkey@racsa.co.cr>
 
+    * Add patch submitted by Dimiter Georgiev to work around problems in building
+      GDB 6.8 with versions of Cygwin > 1.7.
+    * configs/i486-defconfig-4.3.3 - Builds an i486 cross development toolchain
+      using gcc 4.3.3.  Why wouldyou want such a thing?  On Linux, of course,
+      such a thing is not needed because you can use the installed GCC to build
+      i486 ELF binaries.  But that will not work under Cygwin!  The Cygwin
+      toolchain (and probably MinGW), build DOS MZ format executables (i.e.,
+      .exe files).  That is probably not usable for most NuttX targets.
+      Instead, you should use this i486-elf-gcc to generate true ELF binaries
+      under Cygwin.
 </pre></ul>
 
 <table width ="100%">

arch/x86/src/qemu/qemu_fullcontextrestore.S

@@ -111,34 +111,34 @@ SYMBOL(up_fullcontextrestore):
 	 * stack pointer.
 	 */
 
-	movl	(REG_SP)(%eax), %esp
+	movl	(4*REG_SP)(%eax), %esp
 
 	/* Save the return address, EFLAGS, and the values  as well the
 	 * values of EBX and EAC on the new stack.
 	 */
 
-	movl	(REG_EIP)(%eax), %ebx
+	movl	(4*REG_EIP)(%eax), %ebx
 	push	%ebx
-	movl	(REG_EFLAGS)(%eax), %ebx
+	movl	(4*REG_EFLAGS)(%eax), %ebx
 	push	%ebx
-	movl	(REG_EAX)(%eax), %ebx
+	movl	(4*REG_EAX)(%eax), %ebx
 	push	%ebx
-	movl	(REG_EBX)(%eax), %ebx
+	movl	(4*REG_EBX)(%eax), %ebx
 	push	%ebx
 
 	/* Now restore the remaining registers */
 
-	movl	(REG_EDI)(%ebx), %edi
-	movl	(REG_ESI)(%ebx), %esi
-	movl	(REG_EBP)(%ebx), %ebp
-	movl	(REG_EDX)(%ebx), %edx
-	movl	(REG_ECX)(%ebx), %ecx
+	movl	(4*REG_EDI)(%ebx), %edi
+	movl	(4*REG_ESI)(%ebx), %esi
+	movl	(4*REG_EBP)(%ebx), %ebp
+	movl	(4*REG_EDX)(%ebx), %edx
+	movl	(4*REG_ECX)(%ebx), %ecx
 
 	/* Restore the segment registers */
 
-	mov		(REG_DS)(%ebx), %ds
-	mov		(REG_CS)(%ebx), %cs
-	mov		(REG_SS)(%ebx), %ss
+	mov		(4*REG_DS)(%ebx), %ds
+	mov		(4*REG_CS)(%ebx), %cs
+	mov		(4*REG_SS)(%ebx), %ss
 
 	/* Restore the correct value of EAX, EBX, and the EFLAGS then return */
 

arch/x86/src/qemu/qemu_saveusercontext.S

@@ -121,37 +121,37 @@ SYMBOL(up_saveusercontext):
 	 * because it will be the return value from this function.
 	 */
 
-	movl	%ebx, (REG_EBX)(%eax)
-	movl	%esi, (REG_ESI)(%eax)
-	movl	%edi, (REG_EDI)(%eax)
+	movl	%ebx, (4*REG_EBX)(%eax)
+	movl	%esi, (4*REG_ESI)(%eax)
+	movl	%edi, (4*REG_EDI)(%eax)
 
 	/* Save the segment registers */
 
-	mov		%ss, (REG_SS)(%eax)
-	mov		%cs, (REG_CS)(%eax)
-	mov		%ds, (REG_DS)(%eax)
+	mov		%ss, (4*REG_SS)(%eax)
+	mov		%cs, (4*REG_CS)(%eax)
+	mov		%ds, (4*REG_DS)(%eax)
 
 	/* Save the value of SP as will be after we return (don't bother to save
 	 * REG_ESP).
 	 */
 
 	leal	4(%esp), %ecx
-	movl	%ecx, (REG_SP)(%eax)
+	movl	%ecx, (4*REG_SP)(%eax)
 
 	/* Fetch the PC from the stack and save it in the save block */
 
 	movl	0(%esp), %ecx
-	movl	%ecx, (REG_EIP)(%eax)
+	movl	%ecx, (4*REG_EIP)(%eax)
 
 	/* Save the framepointer */
 
-	movl	%ebp, (REG_EBP)(%eax)
+	movl	%ebp, (4*REG_EBP)(%eax)
 
     /* Get and save the interrupt state */
 
     pushf
     pop		%ecx
-	movl	%ecx, (REG_EFLAGS)(%eax)
+	movl	%ecx, (4*REG_EFLAGS)(%eax)
  
 	/* And return 0.  'ret' will remove the EIP from the top of the stack. */
 

configs/qemu-i486/README.txt

@@ -8,6 +8,7 @@ Contents
 ^^^^^^^^
 
   * QEMU
+  * Toolchains
   * Configurations
 
 QEMU
@@ -51,6 +52,57 @@ Cygwin build problems:
 	   binaries.  I found 0.14.0 here: http://dietpc.org/windows/qemu/, or
 	2. Try building QEMU with MingGW
 
+Toolchains
+^^^^^^^^^^
+
+  Two target environments are supported: (1) Linux and (2) Cygwin under Windows.
+  Any GCC toolchain that can produce i486 ELF binaries should work.  On Linux,
+  you can probably use the installed system gcc.  But that will not work with
+  Cygwin.  Why?  Because the Cygwin gcc (and probably the MinGW gcc as well) do
+  not produce ELF final binaries but, rather, DOS MZ executables (i.e., .exe
+  files).  Those cannot be used with QEMU.
+
+  The file */setenv.sh should be modified to point to the correct path to the
+  GCC toolchain (if different from the default in your PATH variable).
+
+  Cygwin Buildroot Toolchain
+
+  With Cygwin the solution is to build an i486 cross-development toolchain to
+  generate the i486 ELF files needed by QEMU.  The NuttX buildroot package will
+  create such a toolchain.
+
+  NOTE: As of this writing, none of the released buildroot packages support the
+  i486 build.  This is only available in SVN or in any any 1.10 or later buildroot
+  release.
+
+  Buildroot Instructions
+
+  1. You must have already configured Nuttx in <some-dir>/nuttx.
+
+     cd tools
+     ./configure.sh qemu-i486/<sub-dir>
+
+  2. Download the latest buildroot package into <some-dir>
+
+  3. unpack the buildroot tarball.  The resulting directory may
+     have versioning information on it like buildroot-x.y.z.  If so,
+     rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot.
+
+  4. cd <some-dir>/buildroot
+
+  5. cp configs/i486-defconfig-4.3.3 .config
+
+  6. make oldconfig
+
+  7. make
+
+  8. Edit setenv.h, if necessary, so that the PATH variable includes
+     the path to the newly built binaries.
+
+  See the file configs/README.txt in the buildroot source tree.  That has more
+  detailed PLUS some special instructions that you will need to follow if you
+  run into problems building the toolchain for Cygwin under Windows.
+
 Configurations
 ^^^^^^^^^^^^^^
 

configs/qemu-i486/ostest/ld.script

@@ -33,6 +33,7 @@
  *
  ****************************************************************************/
 
+OUTPUT_ARCH(elf_i386)
 ENTRY(__start)
 SECTIONS
 {