Linux loader for the PPC

Linux loader for the PPC

[Marco Gerards]

Hi,

Here is, as promised, the linux loader for the PPC.  Just like Tomas
did for the PC, I made the loader accessible from both rescue mode and
normal mode.  There is just one bug in this code, when a kernel is
loaded it is not possible to load another kernel (which should replace
the previous loaded kernel).  I think that problem is caused by a bug
elsewhere in GRUB 2.  

The biggest missing feature in this loader is initrd support.  It is
just 30 minutes hacking at most, but I simply don't have a
kernel+initrd around to test it with.  Most code is already there and
it won't be hard for me to add this later.

If you can not test the patch, please proof read it for me.  I started
too long at this code to be sure that I did the right stuff. ;)

I really hope people will try this to boot GNU/Linux from GRUB 2 on
the PPC.  At the moment only module loading and HFS+ support is
missing.  After that just a few small features should be added to
make this port complete.

If I don't hear any complaints, I will commit this patch tomorrow or
so.

Thanks,
Marco



2004-07-13  Marco Gerards  <metgerards@student.han.nl>

	* boot/powerpc/ieee1275/ieee1275.c (grub_ieee1275_release): New
	function.
	* commands/boot.c: Remove the check for `GRUB_UTIL'.
	* conf/powerpc-ieee1275.rmk (grubof_SOURCES): Add
	`loader/powerpc/ieee1275/linux.c',
	`loader/powerpc/ieee1275/linux_normal.c' and `commands/boot.c'.
	* include/grub/powerpc/ieee1275/ieee1275.h
	(grub_ieee1275_release): New prototype.
	* include/grub/powerpc/ieee1275/loader.h: Rewritten.
	* kern/powerpc/ieee1275/init.c (grub_machine_init): Initialize
	normal, boot, linux and linux_normal.
	* loader/powerpc/ieee1275/linux.c: New file.
	* loader/powerpc/ieee1275/linux_normal.c: Likewise.


diff -uprN ../grub2/boot/powerpc/ieee1275/ieee1275.c ./boot/powerpc/ieee1275/ieee1275.c
--- ../grub2/boot/powerpc/ieee1275/ieee1275.c	2004-04-04 15:45:59.000000000 +0200
+++ ./boot/powerpc/ieee1275/ieee1275.c	2004-07-13 16:40:59.000000000 +0200
@@ -420,6 +420,25 @@ grub_ieee1275_claim (void *p, grub_size_
 }
 
 int
+grub_ieee1275_release (void *p, grub_size_t size)
+{
+ struct release_args {
+    struct grub_ieee1275_common_hdr common;
+    void *p;
+    grub_size_t size;
+ } args;
+
+  INIT_IEEE1275_COMMON (&args.common, "release", 2, 0);
+  args.p = p;
+  args.size = size;
+  
+  if (IEEE1275_CALL_ENTRY_FN (&args) == -1)
+    return -1;
+  
+  return 0;
+}
+
+int
 grub_ieee1275_set_property (grub_ieee1275_phandle_t phandle,
 			    const char *propname, void *buf,
 			    grub_size_t size, grub_size_t *actual)
diff -uprN ../grub2/commands/boot.c ./commands/boot.c
--- ../grub2/commands/boot.c	2004-04-04 15:46:00.000000000 +0200
+++ ./commands/boot.c	2004-07-13 16:40:59.000000000 +0200
@@ -37,7 +37,7 @@ grub_cmd_boot (struct grub_arg_list *sta
 }
 
 \f
-#ifdef GRUB_UTIL
+
 void
 grub_boot_init (void)
 {
@@ -50,7 +50,7 @@ grub_boot_fini (void)
 {
   grub_unregister_command ("boot");
 }
-#else /* ! GRUB_UTIL */
+
 GRUB_MOD_INIT
 {
   (void)mod;			/* To stop warning. */
@@ -62,4 +62,4 @@ GRUB_MOD_FINI
 {
   grub_unregister_command ("boot");
 }
-#endif /* ! GRUB_UTIL */
+
diff -uprN ../grub2/conf/powerpc-ieee1275.rmk ./conf/powerpc-ieee1275.rmk
--- ../grub2/conf/powerpc-ieee1275.rmk	2004-05-24 23:32:21.000000000 +0200
+++ ./conf/powerpc-ieee1275.rmk	2004-07-13 16:40:59.000000000 +0200
@@ -41,7 +41,7 @@ grubof_SOURCES = boot/powerpc/ieee1275/c
 	kern/powerpc/ieee1275/openfw.c fs/ext2.c fs/ufs.c fs/minix.c normal/cmdline.c \
 	normal/command.c normal/main.c normal/menu.c \
 	disk/powerpc/ieee1275/ofdisk.c disk/powerpc/ieee1275/partition.c \
-	kern/env.c normal/arg.c
+	kern/env.c normal/arg.c loader/powerpc/ieee1275/linux.c loader/powerpc/ieee1275/linux_normal.c commands/boot.c
 grubof_HEADERS = grub/powerpc/ieee1275/ieee1275.h
 grubof_CFLAGS = $(COMMON_CFLAGS)
 grubof_ASFLAGS = $(COMMON_ASFLAGS)
diff -uprN ../grub2/include/grub/powerpc/ieee1275/ieee1275.h ./include/grub/powerpc/ieee1275/ieee1275.h
--- ../grub2/include/grub/powerpc/ieee1275/ieee1275.h	2004-04-04 15:46:01.000000000 +0200
+++ ./include/grub/powerpc/ieee1275/ieee1275.h	2004-07-13 16:40:59.000000000 +0200
@@ -84,6 +84,7 @@ int EXPORT_FUNC(grub_ieee1275_open) (cha
 int EXPORT_FUNC(grub_ieee1275_close) (grub_ieee1275_ihandle_t ihandle);
 int EXPORT_FUNC(grub_ieee1275_claim) (void *p, grub_size_t size, unsigned int align,
 				      void **result);
+int EXPORT_FUNC(grub_ieee1275_release) (void *p, grub_size_t size);
 int EXPORT_FUNC(grub_ieee1275_set_property) (grub_ieee1275_phandle_t phandle,
 					     const char *propname, void *buf,
 					     grub_size_t size,
diff -uprN ../grub2/include/grub/powerpc/ieee1275/loader.h ./include/grub/powerpc/ieee1275/loader.h
--- ../grub2/include/grub/powerpc/ieee1275/loader.h	2004-04-04 15:46:01.000000000 +0200
+++ ./include/grub/powerpc/ieee1275/loader.h	2004-07-13 16:40:59.000000000 +0200
@@ -1,7 +1,6 @@
 /*
  *  GRUB  --  GRand Unified Bootloader
- *  Copyright (C) 2002  Yoshinori K. Okuji <okuji@enbug.org>
- *  Copyright (C) 2003  Jeroen Dekkers <jeroen@dekkers.cx>
+ *  Copyright (C) 2004  Free Software Foundation, Inc.
  *
  *  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
@@ -21,31 +20,13 @@
 #ifndef GRUB_LOADER_MACHINE_HEADER
 #define GRUB_LOADER_MACHINE_HEADER	1
 
-#include <grub/types.h>
-#include <grub/symbol.h>
-#include <grub/machine/multiboot.h>
-
-extern grub_uint32_t EXPORT_VAR(grub_linux_prot_size);
-extern char *EXPORT_VAR(grub_linux_tmp_addr);
-extern char *EXPORT_VAR(grub_linux_real_addr);
-
-void EXPORT_FUNC(grub_linux_boot_zimage) (void) __attribute__ ((noreturn));
-void EXPORT_FUNC(grub_linux_boot_bzimage) (void) __attribute__ ((noreturn));
-
-/* This is an asm part of the chainloader.  */
-void EXPORT_FUNC(grub_chainloader_real_boot) (int drive, void *part_addr) __attribute__ ((noreturn));
-
-/* The asm part of the multiboot loader.  */
-void EXPORT_FUNC(grub_multiboot_real_boot) (grub_addr_t entry, 
-					    struct grub_multiboot_info *mbi) 
-     __attribute__ ((noreturn));
-
-/* It is necessary to export these functions, because normal mode commands
-   reuse rescue mode commands.  */
-void grub_rescue_cmd_chainloader (int argc, char *argv[]);
-void grub_rescue_cmd_linux (int argc, char *argv[]);
-void grub_rescue_cmd_initrd (int argc, char *argv[]);
-void grub_rescue_cmd_multiboot (int argc, char *argv[]);
-void grub_rescue_cmd_module (int argc, char *argv[]);
+/* The symbol shared between the normal mode and rescue mode
+   loader.  */
+void grub_load_linux (int argc, char *argv[]);
+
+void grub_linux_init (void);
+void grub_linux_fini (void);
+void grub_linux_normal_init (void);
+void grub_linux_normal_fini (void);
 
 #endif /* ! GRUB_LOADER_MACHINE_HEADER */
diff -uprN ../grub2/kern/powerpc/ieee1275/init.c ./kern/powerpc/ieee1275/init.c
--- ../grub2/kern/powerpc/ieee1275/init.c	2004-04-30 22:46:40.000000000 +0200
+++ ./kern/powerpc/ieee1275/init.c	2004-07-13 16:40:59.000000000 +0200
@@ -58,6 +58,10 @@ grub_machine_init (void)
   grub_env_set ("prefix", "");
 
   grub_ext2_init ();
+  grub_normal_init ();
+  grub_boot_init ();
+  grub_linux_init ();
+  grub_linux_normal_init ();
   grub_ofdisk_init ();
   grub_console_init ();
 }
diff -uprN ../grub2/loader/powerpc/ieee1275/linux.c ./loader/powerpc/ieee1275/linux.c
--- ../grub2/loader/powerpc/ieee1275/linux.c	1970-01-01 01:00:00.000000000 +0100
+++ ./loader/powerpc/ieee1275/linux.c	2004-07-13 15:52:00.000000000 +0200
@@ -0,0 +1,289 @@
+/* linux.c - boot Linux */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2003, 2004  Free Software Foundation, Inc.
+ *
+ *  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.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <grub/machine/loader.h>
+#include <grub/machine/ieee1275.h>
+#include <grub/elf.h>
+#include <grub/loader.h>
+#include <grub/dl.h>
+#include <grub/mm.h>
+#include <grub/rescue.h>
+#include <grub/misc.h>
+
+static grub_dl_t my_mod;
+
+static int loaded;
+static int vmlinux;
+
+static grub_addr_t initrd_addr;
+static grub_size_t initrd_size;
+
+static grub_addr_t linux_addr;
+static grub_size_t linux_size;
+
+static char *linux_args;
+
+typedef void (*kernel_entry_t) (void *, unsigned long, intptr_t (void *),
+				unsigned long, unsigned long);
+
+static grub_err_t
+grub_linux_boot (void)
+{
+  kernel_entry_t linuxmain;
+  grub_ieee1275_phandle_t chosen;
+  grub_size_t actual;
+  
+  struct bi_rec
+  {
+    unsigned long tag;
+    unsigned long size;
+    unsigned long data[0];
+  };
+  
+  grub_ieee1275_finddevice ("/chosen", &chosen);
+  
+  /* Set the command line arguments.  */
+  grub_ieee1275_set_property (chosen, "bootargs", linux_args,
+			      grub_strlen (linux_args) + 1, &actual);
+  
+  /* Boot the kernel.  */
+  linuxmain = (kernel_entry_t) linux_addr;
+  linuxmain ((void *) initrd_addr, initrd_size, grub_ieee1275_entry_fn, 0, 0);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+grub_linux_release_mem (void)
+{
+  grub_free (linux_args);
+  linux_args = 0;
+  
+  if (linux_addr && grub_ieee1275_release ((void *) linux_addr, linux_size))
+    return grub_error (GRUB_ERR_OUT_OF_MEMORY, "Can not release memory");
+  
+  linux_addr = 0;
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+grub_linux_unload (void)
+{
+  grub_err_t err;
+  
+  err = grub_linux_release_mem ();
+  grub_dl_unref (my_mod);
+  
+  loaded = 0;
+  
+  return err;
+}
+
+void
+grub_load_linux (int argc, char *argv[])
+{
+  grub_file_t file = 0;
+  Elf32_Ehdr ehdr;
+  Elf32_Phdr *phdrs = 0;
+  int i;  
+  int offset = 0;
+  static grub_addr_t entry;
+  int size;
+  
+  grub_dl_ref (my_mod);
+
+  if (argc == 0)
+    {
+      grub_error (GRUB_ERR_BAD_ARGUMENT, "no kernel specified");
+      goto fail;
+    }
+  
+  file = grub_file_open (argv[0]);
+  if (! file)
+    goto fail;
+  
+  if (grub_file_read (file, (char *) &ehdr, sizeof (ehdr)) != sizeof (ehdr))
+    {
+      grub_error (GRUB_ERR_READ_ERROR, "cannot read the linux elf header");
+      goto fail;
+    }
+  
+  if (!((ehdr.e_ident[EI_MAG0] == ELFMAG0) 
+	&& (ehdr.e_ident[EI_MAG1] == ELFMAG1)
+	&& (ehdr.e_ident[EI_MAG2] == ELFMAG2) 
+	&& (ehdr.e_ident[EI_MAG3] == ELFMAG3)
+	&& (ehdr.e_ident[EI_CLASS] == ELFCLASS32) 
+	&& (ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
+	&& (ehdr.e_ident[EI_VERSION] == EV_CURRENT) 
+	&& (ehdr.e_type == ET_EXEC) && (ehdr.e_machine == EM_PPC) 
+	&& (ehdr.e_version == EV_CURRENT)))
+    {
+      grub_error (GRUB_ERR_UNKNOWN_OS, "No valid ELF header found");
+      goto fail;
+    }
+  
+  if (ehdr.e_type != ET_EXEC)
+    {
+      grub_error (GRUB_ERR_UNKNOWN_OS,
+		  "This ELF file is not of the right type\n");
+      goto fail;
+    }
+
+  if (ehdr.e_machine != EM_PPC)
+    {
+      grub_error (GRUB_ERR_UNKNOWN_OS,
+		  "This ELF file is not for the PPC32\n");
+      goto fail;
+    }
+  
+  if (ehdr.e_version != EV_CURRENT)
+    {
+      grub_error (GRUB_ERR_UNKNOWN_OS,
+		  "Invalid ELF version\n");
+      goto fail;
+    }
+
+  /* Read the sections.  */
+  entry = ehdr.e_entry;
+  if (entry == 0xc0000000)
+    {
+      entry = 0x01400000;
+      vmlinux = 1;
+    }
+  else
+    vmlinux = 0;
+
+  phdrs = (Elf32_Phdr *) grub_malloc (ehdr.e_phnum * ehdr.e_phentsize);
+  grub_file_read (file, (void *) phdrs, ehdr.e_phnum * ehdr.e_phentsize);
+  
+  /* Release the previously used memory.  */
+  grub_loader_unset ();
+  
+  /* Determine the amount of memory that is required.  */
+  linux_size = 0;
+  for (i = 0; i < ehdr.e_phnum; i++)
+    {
+      Elf32_Phdr *phdr = phdrs + i;
+      /* XXX: Is this calculation correct?  */
+      linux_size += phdr->p_memsz + phdr->p_filesz;
+    }
+  
+  /* Reserve memory for the kernel.  */
+  linux_size += 0x100000;
+  
+  if (grub_ieee1275_claim ((void *) entry, linux_size, 0, (void *) &linux_addr) == -1)
+    {
+      grub_error (GRUB_ERR_OUT_OF_MEMORY, "Can not claim memory");
+      goto fail;
+    }
+  
+  /* Load every loadable segment in memory.  */
+  for (i = 0; i < ehdr.e_phnum; i++)
+    {
+      Elf32_Phdr *phdr = phdrs + i;
+
+      if (phdr->p_type == PT_LOAD)
+	{
+	  if (grub_file_seek (file, phdr->p_offset) == -1)
+	    {
+	      grub_error (GRUB_ERR_BAD_OS, "Invalid offset in program header");
+	      goto fail;
+	    }
+	  
+	  if (grub_file_read (file, (void *) (((char *) entry) + offset) , phdr->p_filesz) 
+	      != (grub_ssize_t) phdr->p_filesz)
+	    goto fail;
+	  
+	  if (phdr->p_filesz < phdr->p_memsz)
+	    grub_memset ((char *) (((char *) entry) + offset) + phdr->p_filesz, 0, 
+			 phdr->p_memsz - phdr->p_filesz);
+
+	  offset += phdr->p_filesz;
+	}
+    }
+  
+  size = 0;
+  for (i = 0; i < argc; i++)
+    size += grub_strlen (argv[i]);
+  
+  linux_args = grub_malloc (size + argc + 1);
+  if (!linux_args)
+    goto fail;
+  
+  for (i = 1; i < argc; i++)
+    {
+      grub_strcat (linux_args, argv[i]);
+      grub_strcat (linux_args, " ");
+    }
+  
+ fail:
+
+  if (file)
+    grub_file_close (file);
+  
+  grub_free (phdrs);
+
+  if (grub_errno != GRUB_ERR_NONE)
+    {
+      grub_linux_release_mem ();
+      grub_dl_unref (my_mod);
+      loaded = 0;
+    }
+  else
+    {
+      grub_loader_set (grub_linux_boot, grub_linux_unload);
+      initrd_addr = 0xc0000000;
+      loaded = 1;
+    }
+  
+  return;
+}
+
+\f
+static void
+grub_rescue_cmd_linux (int argc, char *argv[])
+{
+  grub_load_linux (argc, argv);
+}
+
+GRUB_MOD_INIT
+{
+  grub_rescue_register_command ("linux", grub_rescue_cmd_linux,
+				"load a linux kernel");
+  my_mod = mod;
+}
+
+GRUB_MOD_FINI
+{
+  grub_rescue_unregister_command ("linux");
+}
+
+void
+grub_linux_init (void)
+{
+  grub_rescue_register_command ("linux", grub_rescue_cmd_linux,
+				"load a linux kernel");
+}
+
+void
+grub_linux_fini (void)
+{
+  grub_rescue_unregister_command ("linux");
+}
diff -uprN ../grub2/loader/powerpc/ieee1275/linux_normal.c ./loader/powerpc/ieee1275/linux_normal.c
--- ../grub2/loader/powerpc/ieee1275/linux_normal.c	1970-01-01 01:00:00.000000000 +0100
+++ ./loader/powerpc/ieee1275/linux_normal.c	2004-07-13 15:45:10.000000000 +0200
@@ -0,0 +1,63 @@
+/* linux_normal.c - boot Linux */
+/*
+ *  GRUB  --  Preliminary Universal Programming Architecture for GRUB
+ *  Copyright (C) 2004  Free Software Foundation, Inc.
+ *
+ *  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.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <grub/normal.h>
+#include <grub/dl.h>
+#include <grub/machine/loader.h>
+
+static const struct grub_arg_option options[] =
+  {
+    {0, 0, 0, 0, 0, 0}
+  };
+
+static grub_err_t
+grub_cmd_linux (struct grub_arg_list *state  __attribute__ ((unused)),
+		int argc, char **args)
+{
+  grub_load_linux (argc, args);
+  return GRUB_ERR_NONE;
+}
+
+GRUB_MOD_INIT
+{
+  (void) mod;
+  grub_register_command ("linux", grub_cmd_linux, GRUB_COMMAND_FLAG_BOTH,
+			 "linux [KERNELARGS...]",
+			 "Loads linux", options);
+}
+
+GRUB_MOD_FINI
+{
+  grub_unregister_command ("linux");
+}
+
+void
+grub_linux_normal_init (void)
+{
+  grub_register_command ("linux", grub_cmd_linux, GRUB_COMMAND_FLAG_BOTH,
+			 "linux [KERNELARGS...]",
+			 "Loads linux", options);
+}
+
+void
+grub_linux_normal_fini (void)
+{
+  grub_unregister_command ("linux");
+}

Re: Linux loader for the PPC

[Jeroen Dekkers]

At Tue, 13 Jul 2004 19:01:22 +0200,
Marco Gerards wrote:
> +static void
> +grub_rescue_cmd_linux (int argc, char *argv[])
> +{
> +  grub_load_linux (argc, argv);
> +}
> +
> +GRUB_MOD_INIT
> +{
> +  grub_rescue_register_command ("linux", grub_rescue_cmd_linux,
> +				"load a linux kernel");
> +  my_mod = mod;
> +}

Why don't you just use grub_load_linux as argument to
grub_rescue_register_command()?

Jeroen Dekkers

Re: Linux loader for the PPC

[Marco Gerards]

Jeroen Dekkers <jeroen@dekkers.cx> writes:

> At Tue, 13 Jul 2004 19:01:22 +0200,
> Marco Gerards wrote:
>> +static void
>> +grub_rescue_cmd_linux (int argc, char *argv[])
>> +{
>> +  grub_load_linux (argc, argv);
>> +}
>> +
>> +GRUB_MOD_INIT
>> +{
>> +  grub_rescue_register_command ("linux", grub_rescue_cmd_linux,
>> +				"load a linux kernel");
>> +  my_mod = mod;
>> +}
>
> Why don't you just use grub_load_linux as argument to
> grub_rescue_register_command()?

Because that will make it harder to change the interface of
grub_load_linux afterwards.

--
Marco

Re: Linux loader for the PPC

[Jeroen Dekkers]

At Tue, 13 Jul 2004 21:03:09 +0200,
Marco Gerards wrote:
> 
> Jeroen Dekkers <jeroen@dekkers.cx> writes:
> 
> > At Tue, 13 Jul 2004 19:01:22 +0200,
> > Marco Gerards wrote:
> >> +static void
> >> +grub_rescue_cmd_linux (int argc, char *argv[])
> >> +{
> >> +  grub_load_linux (argc, argv);
> >> +}
> >> +
> >> +GRUB_MOD_INIT
> >> +{
> >> +  grub_rescue_register_command ("linux", grub_rescue_cmd_linux,
> >> +				"load a linux kernel");
> >> +  my_mod = mod;
> >> +}
> >
> > Why don't you just use grub_load_linux as argument to
> > grub_rescue_register_command()?
> 
> Because that will make it harder to change the interface of
> grub_load_linux afterwards.

Why? It's in the same file as the register command. If it gets a
different interface, you can update the register call with it to
point to some new function that wraps is.

Jeroen Dekkers

Re: Linux loader for the PPC

[Marco Gerards]

Jeroen Dekkers <jeroen@dekkers.cx> writes:

>> > Why don't you just use grub_load_linux as argument to
>> > grub_rescue_register_command()?
>> 
>> Because that will make it harder to change the interface of
>> grub_load_linux afterwards.
>
> Why? It's in the same file as the register command. If it gets a
> different interface, you can update the register call with it to
> point to some new function that wraps is.

Well, ok.  I have no strong opinion about it.  I can change this
before committing the patch.

Anything else? :)

--
Marco

Re: Linux loader for the PPC

[Marco Gerards]

Marco Gerards <metgerards@student.han.nl> writes:

> Here is, as promised, the linux loader for the PPC.  Just like Tomas
> did for the PC, I made the loader accessible from both rescue mode and
> normal mode.  There is just one bug in this code, when a kernel is
> loaded it is not possible to load another kernel (which should replace
> the previous loaded kernel).  I think that problem is caused by a bug
> elsewhere in GRUB 2.  

I just committed this (Better late then never ;)).

I did not commit hfs support yet because I want to finish hfs+ support
first.  Unless someone has a good reason for me to commit it now.
This can take quite a while before I will finish it.

So now GRUB 2 can be used to boot GNU/Linux on the open firmware PPCs.

If I am not mistaken, Maurizio is working on module loaded for this
port (what is the status, btw?).  Hopefully soon I will find the time
to finish the interface so it becomes easy to use GRUB 2.  The last
important missing feature is a loader for macos.  And we will need
multiboot support, of course.

I really hope anyone reading this with a PPC will test this code and
tell me which features are missing.  If there is any mac/ppc specific
feature that is not implemented or mentioned that will most likely
mean it will not be implemented.  So don't be shy and tell me what you
need.

And to make it ready for production usage someday, GRUB 2 on the PPC
needs to be tested.  You can do that by following these steps (a=disk,
b=network):

1) Make a CVS checkout of GRUB 2.

2) ./configure && make

3a) Copy grubof to your HFS[+] boot partition.  This is the same
    partition yaboot uses.

3b) Copy grubof to your tftp directory.  Setup bootp to load this
    kernel.

4a) Boot your mac into the open firmware console and boot the grubof
    ELF.
4b) Boot from network.

5)  GRUB is started.  You can load and boot GNU/Linux using (for example):

linux (hd,10)/vmlinux root=/dev/hda11
boot

6)  Or instead of booting just play a bit.  Try to access files and
    find bugs. :)

Please send me a report if this does or doesn't work for you.  What
went wrong, etc.  It would be useful for me to hear what kind of
machine you were using.

Thanks,
Marco