[MULTIBOOT2 SPEC PATCH v3 0/4] multiboot2: Clean up the example kernel

* [MULTIBOOT2 SPEC PATCH v3 0/4] multiboot2: Clean up the example kernel
@ 2020-05-08  4:50 Hans Ulrich Niedermann
  2020-05-08  4:50 ` [MULTIBOOT2 SPEC PATCH v3 1/4] multiboot2: Allow autogen.sh to run with current gnulib Hans Ulrich Niedermann
                   ` (3 more replies)
  0 siblings, 4 replies; 13+ messages in thread
From: Hans Ulrich Niedermann @ 2020-05-08  4:50 UTC (permalink / raw)
  To: grub-devel; +Cc: Hans Ulrich Niedermann

This cleans up the Multiboot2 example kernel in a few ways:

  * It fixes the build with current gnulib.

  * Change from obsolete .bzrignore to .gitignore.

  * It fixes the build on non-MIPS systems such as x86.

  * It fixes the Multiboot2 header tag alignment in the
    assembly language boot_*.S files to 8 byte boundaries.

  * It fixes the alignment in boot_mips.S to align to 8 byte
    boundaries instead of 256 byte boundaries.

This is v3 of a previous patch set. The differences mainly are

  * improved .gitignore

  * fix the case logic for the ix86 matching pattern ([[]])

  * fix mb2 header tag alignment

  * fix alignment on mips

I am posting this right now to make clear that my previous patch
set version v1/v2 had issues, but this v3 certainly can use some
improvement as well. Also, this is not very urgent, so putting
this off until after the next GRUB release is very reasonable.

Hans Ulrich Niedermann (4):
  multiboot2: Allow autogen.sh to run with current gnulib
  multiboot2: Use .gitignore files
  multiboot2: Make example kernel build at least for i386
  multiboot2: fix example kernel header tag alignment

 .bzrignore                  | 30 -------------------
 .gitignore                  | 51 ++++++++++++++++++++++++++++++++
 configure.ac                | 37 +++++++++++++++++++----
 doc/.gitignore              |  2 ++
 doc/Makefile.am             |  9 +++---
 doc/{boot.S => boot_i386.S} |  9 ++++--
 doc/boot_mips.S             | 17 +++++++----
 doc/multiboot.texi          | 59 +++++++++++++++++++++++--------------
 8 files changed, 144 insertions(+), 70 deletions(-)
 delete mode 100644 .bzrignore
 create mode 100644 .gitignore
 create mode 100644 doc/.gitignore
 rename doc/{boot.S => boot_i386.S} (93%)

Interdiff:

diff --git a/.gitignore b/.gitignore
index bd387ea77..4de19ceee 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-# Generated by autogen.sh
+# Generated by "autogen.sh"
 /gendocs.sh
 /lib/
 /m4/
@@ -6,6 +6,8 @@
 /NEWS
 /README
 
+Makefile.in
+
 /aclocal.m4
 /autom4te.cache/
 /compile
@@ -20,9 +22,7 @@
 /INSTALL
 /missing
 
-Makefile.in
-
-# Generated by configure
+# Generated by "configure"
 Makefile
 .deps/
 
@@ -31,7 +31,7 @@ Makefile
 /config.status
 /stamp-h1
 
-# Generated by make
+# Generated by "make"
 /doc/*.c.texi
 /doc/*.h.texi
 /doc/*.S.texi
@@ -40,4 +40,12 @@ Makefile
 /doc/version.texi
 
 *.o
+
 /doc/kernel
+
+# Generated by "make web-manual"
+/doc/manual/
+/doc/multiboot.aux
+/doc/multiboot.cp
+/doc/multiboot.log
+/doc/multiboot.toc
diff --git a/configure.ac b/configure.ac
index ee648f52a..5ddb16b72 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,17 +34,23 @@ AC_SUBST(CCAS)
 
 dnl Build the example Multiboot kernel (if possible on this host)
 AC_CANONICAL_HOST
-case "$host" in #(
-  i[3456]86-*) kernel_boot_arch=i386
-               ;; #(
-  x86_64-*)    kernel_boot_arch=i386
-               kernel_ccasflags="-m32"
-               kernel_cflags="-m32"
-	       ;; #(
-  mips-*)      kernel_boot_arch=mips
-               ;; #(
-  *)           kernel_boot_arch=unsupported
-               ;;
+kernel_ccasflags=
+kernel_cflags=
+case "$host_cpu" in #(
+  i[[3456]]86)
+    kernel_boot_arch=i386
+    ;; #(
+  x86_64)
+    kernel_boot_arch=i386
+    kernel_ccasflags="-m32"
+    kernel_cflags="-m32"
+    ;; #(
+  mips*)
+    kernel_boot_arch=mips
+    ;; #(
+  *)
+    kernel_boot_arch=unsupported
+    ;;
 esac
 AC_SUBST([kernel_boot_arch])
 AC_SUBST([kernel_ccasflags])
diff --git a/doc/boot_i386.S b/doc/boot_i386.S
index 9ab016612..1418afe1a 100644
--- a/doc/boot_i386.S
+++ b/doc/boot_i386.S
@@ -56,6 +56,7 @@ multiboot_header:
 	/* checksum */
 	.long	-(MULTIBOOT2_HEADER_MAGIC + MULTIBOOT_ARCHITECTURE_I386 + (multiboot_header_end - multiboot_header))
 #ifndef __ELF__
+	.align	8
 address_tag_start:	
 	.short MULTIBOOT_HEADER_TAG_ADDRESS
 	.short MULTIBOOT_HEADER_TAG_OPTIONAL
@@ -69,6 +70,7 @@ address_tag_start:
 	/* bss_end_addr */
 	.long	_end
 address_tag_end:
+	.align	8
 entry_address_tag_start:	
 	.short MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS
 	.short MULTIBOOT_HEADER_TAG_OPTIONAL
@@ -77,6 +79,7 @@ entry_address_tag_start:
 	.long multiboot_entry
 entry_address_tag_end:
 #endif /* __ELF__ */
+	.align	8
 framebuffer_tag_start:	
 	.short MULTIBOOT_HEADER_TAG_FRAMEBUFFER
 	.short MULTIBOOT_HEADER_TAG_OPTIONAL
@@ -85,10 +88,12 @@ framebuffer_tag_start:
 	.long 768
 	.long 32
 framebuffer_tag_end:
+	.align	8
 	.short MULTIBOOT_HEADER_TAG_END
 	.short 0
 	.long 8
 multiboot_header_end:
+
 multiboot_entry:
 	/* Initialize the stack pointer.  */
 	movl	$(stack + STACK_SIZE), %esp
diff --git a/doc/boot_mips.S b/doc/boot_mips.S
index ed604214d..e7bb7df9f 100644
--- a/doc/boot_mips.S
+++ b/doc/boot_mips.S
@@ -46,8 +46,8 @@ _start:
 	 nop
 
 	/* Align 64 bits boundary.  */
-	.align	8
-	
+	.balign	8
+
 	/* Multiboot header.  */
 multiboot_header:
 	/* magic */
@@ -59,7 +59,8 @@ multiboot_header:
 	/* checksum */
 	.long	-(MULTIBOOT2_HEADER_MAGIC + MULTIBOOT_ARCHITECTURE_MIPS32 + (multiboot_header_end - multiboot_header))
 #ifndef __ELF__
-address_tag_start:	
+	.balign	8
+address_tag_start:
 	.short MULTIBOOT_HEADER_TAG_ADDRESS
 	.short MULTIBOOT_HEADER_TAG_OPTIONAL
 	.long address_tag_end - address_tag_start
@@ -72,7 +73,8 @@ address_tag_start:
 	/* bss_end_addr */
 	.long	_end
 address_tag_end:
-entry_address_tag_start:	
+	.balign	8
+entry_address_tag_start:
 	.short MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS
 	.short MULTIBOOT_HEADER_TAG_OPTIONAL
 	.long entry_address_tag_end - entry_address_tag_start
@@ -80,7 +82,8 @@ entry_address_tag_start:
 	.long multiboot_entry
 entry_address_tag_end:
 #endif /* __ELF__ */
-framebuffer_tag_start:	
+	.balign	8
+framebuffer_tag_start:
 	.short MULTIBOOT_HEADER_TAG_FRAMEBUFFER
 	.short MULTIBOOT_HEADER_TAG_OPTIONAL
 	.long framebuffer_tag_end - framebuffer_tag_start
@@ -88,10 +91,12 @@ framebuffer_tag_start:
 	.long 768
 	.long 32
 framebuffer_tag_end:
+	.balign	8
 	.short MULTIBOOT_HEADER_TAG_END
 	.short 0
 	.long 8
 multiboot_header_end:
+
 multiboot_entry:
 	/* Initialize the stack pointer.  */
 	lui     $sp, %hi (stack + STACK_SIZE)
@@ -114,6 +119,6 @@ loop:	nop
 halt_message:
 	.asciz	"Halted."
 
-	.align 8
+	.balign 8
 	/* Our stack area.  */
 	.comm	stack, STACK_SIZE
diff --git a/doc/multiboot.texi b/doc/multiboot.texi
index c70d9239e..827a5c08d 100644
--- a/doc/multiboot.texi
+++ b/doc/multiboot.texi
@@ -1566,12 +1566,12 @@ executes @file{boot_*.S}, it initializes the stack pointer and
 
 If @code{cmain} returns to the callee, then it shows a message to
 inform the user of the halt state and stops forever until you push the
-reset key. The file @file{kernel.c} contains the function
+system reset button. The file @file{kernel.c} contains the function
 @code{cmain}, which checks if the magic number passed by the boot
 loader is valid and so on, and some functions to print messages on the
-screen. The file @file{multiboot2.h} defines some macros, such as the
-magic number for the Multiboot2 header, the Multiboot2 header
-structure and the Multiboot2 information structure.
+screen. The file @file{multiboot2.h} defines some C preprocessor
+macros, such as the magic number for the Multiboot2 header, the
+Multiboot2 header structure and the Multiboot2 information structure.
 
 @menu
 * multiboot2.h::
-- 
2.26.2



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