[U-Boot,v2,2/4] cmd_bootm.c: Add 'booti' for ARM64 Linux kernel Images

Message ID 1408012958-17970-2-git-send-email-trini@ti.com
State Accepted
Delegated to: Tom Rini
Headers show

Commit Message

Tom Rini Aug. 14, 2014, 10:42 a.m.
The default format for arm64 Linux kernels is the "Image" format,
described in Documentation/arm64/booting.txt.  This, along with an
optional gzip compression on top is all that is generated by default.
The Image format has a magic number within the header for verification,
a text_offset where the Image must be run from, an image_size that
includes the BSS and reserved fields.

This does not support automatic detection of a gzip compressed image.

Signed-off-by: Tom Rini <trini@ti.com>

---
Changes in v1:
- Adopt to Mark Rutland's changes now in mainline kernel wrt text_offset
  / image_size
---
 README             |    1 +
 common/cmd_bootm.c |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/bootm.h    |    2 +-
 3 files changed, 142 insertions(+), 1 deletion(-)

Comments

Mark Rutland Aug. 14, 2014, 3:16 p.m. | #1
Hi Tom,

On Thu, Aug 14, 2014 at 11:42:36AM +0100, Tom Rini wrote:
> The default format for arm64 Linux kernels is the "Image" format,
> described in Documentation/arm64/booting.txt.  This, along with an
> optional gzip compression on top is all that is generated by default.
> The Image format has a magic number within the header for verification,
> a text_offset where the Image must be run from, an image_size that
> includes the BSS and reserved fields.
> 
> This does not support automatic detection of a gzip compressed image.
> 
> Signed-off-by: Tom Rini <trini@ti.com>
> 
> ---
> Changes in v1:
> - Adopt to Mark Rutland's changes now in mainline kernel wrt text_offset
>   / image_size
> ---
>  README             |    1 +
>  common/cmd_bootm.c |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/bootm.h    |    2 +-
>  3 files changed, 142 insertions(+), 1 deletion(-)
> 
> diff --git a/README b/README
> index 1d71359..b9af7ac 100644
> --- a/README
> +++ b/README
> @@ -959,6 +959,7 @@ The following options need to be configured:
>  		CONFIG_CMD_BMP		* BMP support
>  		CONFIG_CMD_BSP		* Board specific commands
>  		CONFIG_CMD_BOOTD	  bootd
> +		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
>  		CONFIG_CMD_CACHE	* icache, dcache
>  		CONFIG_CMD_CLK   	* clock command support
>  		CONFIG_CMD_CONSOLE	  coninfo
> diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
> index 8b897c8d..843ec6e 100644
> --- a/common/cmd_bootm.c
> +++ b/common/cmd_bootm.c
> @@ -627,3 +627,143 @@ U_BOOT_CMD(
>  	"boot Linux zImage image from memory", bootz_help_text
>  );
>  #endif	/* CONFIG_CMD_BOOTZ */
> +
> +#ifdef CONFIG_CMD_BOOTI
> +/* See Documentation/arm64/booting.txt in the Linux kernel */
> +struct Image_header {
> +	uint32_t	code0;		/* Executable code */
> +	uint32_t	code1;		/* Executable code */
> +	uint64_t	text_offset;	/* Image load offset, LE */
> +	uint64_t	image_size;	/* Effective Image size, LE */
> +	uint64_t	res1;		/* reserved */
> +	uint64_t	res2;		/* reserved */
> +	uint64_t	res3;		/* reserved */
> +	uint64_t	res4;		/* reserved */
> +	uint32_t	magic;		/* Magic number */
> +	uint32_t	res5;
> +};
> +
> +#define LINUX_ARM64_IMAGE_MAGIC	0x644d5241
> +
> +static int booti_setup(bootm_headers_t *images)
> +{
> +	struct Image_header *ih;
> +	uint64_t dst;
> +
> +	ih = (struct Image_header *)map_sysmem(images->ep, 0);
> +
> +	if (ih->magic != le32_to_cpu(LINUX_ARM64_IMAGE_MAGIC)) {
> +		puts("Bad Linux ARM64 Image magic!\n");
> +		return 1;
> +	}
> +	
> +	if (ih->image_size == 0) {
> +		puts("Image lacks image_size field, assuming 16MiB\n");
> +		ih->image_size = (16 << 20);
> +	}

This should work for a defconfig, but it might be possible to build a
larger kernel. From experiments with an allyesconfig, I can build a
~60MB kernel with ~20MB of uninitialised data after the end of the
Image.

Modifying the Image feels a little dodgy, but I can't think of anything
this would break.

> +
> +	/*
> +	 * If we are not at the correct run-time location, set the new
> +	 * correct location and then move the image there.
> +	 */
> +	dst = gd->bd->bi_dram[0].start + le32_to_cpu(ih->text_offset);

This should be le64_to_cpu(ih->text_offset) to be strictly correct.

I wouldn't imagine we'd ever have a text_offset larger than 4GB, but it
would be nice to keep things consistent with the documentation and
kernel code.

> +	if (images->ep != dst) {
> +		void *src;
> +
> +		debug("Moving Image from 0x%lx to 0x%llx\n", images->ep, dst);
> +
> +		src = (void *)images->ep;
> +		images->ep = dst;
> +		memmove((void *)dst, src, le32_to_cpu(ih->image_size));

Likewise.

> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Image booting support
> + */
> +static int booti_start(cmd_tbl_t *cmdtp, int flag, int argc,
> +			char * const argv[], bootm_headers_t *images)
> +{
> +	int ret;
> +	struct Image_header *ih;
> +
> +	ret = do_bootm_states(cmdtp, flag, argc, argv, BOOTM_STATE_START,
> +			      images, 1);
> +
> +	/* Setup Linux kernel Image entry point */
> +	if (!argc) {
> +		images->ep = load_addr;
> +		debug("*  kernel: default image load address = 0x%08lx\n",
> +				load_addr);
> +	} else {
> +		images->ep = simple_strtoul(argv[0], NULL, 16);
> +		debug("*  kernel: cmdline image address = 0x%08lx\n",
> +			images->ep);
> +	}
> +
> +	ret = booti_setup(images);
> +	if (ret != 0)
> +		return 1;
> +
> +	ih = (struct Image_header *)map_sysmem(images->ep, 0);
> +
> +	lmb_reserve(&images->lmb, images->ep, le32_to_cpu(ih->image_size));

Likewise.

[...]

> +#ifdef CONFIG_SYS_LONGHELP
> +static char booti_help_text[] =
> +	"[addr [initrd[:size]] [fdt]]\n"
> +	"    - boot Linux Image stored in memory\n"
> +	"\tThe argument 'initrd' is optional and specifies the address\n"
> +	"\tof the initrd in memory. The optional argument ':size' allows\n"
> +	"\tspecifying the size of RAW initrd.\n"
> +#if defined(CONFIG_OF_LIBFDT)
> +	"\tSince booting a Linux kernelrequires a flat device-tree\n"

Nit: space between "kernel" and "requires"

Thanks,
Mark.
Tom Rini Aug. 14, 2014, 7:11 p.m. | #2
On Thu, Aug 14, 2014 at 04:16:50PM +0100, Mark Rutland wrote:
> Hi Tom,
> 
> On Thu, Aug 14, 2014 at 11:42:36AM +0100, Tom Rini wrote:
> > The default format for arm64 Linux kernels is the "Image" format,
> > described in Documentation/arm64/booting.txt.  This, along with an
> > optional gzip compression on top is all that is generated by default.
> > The Image format has a magic number within the header for verification,
> > a text_offset where the Image must be run from, an image_size that
> > includes the BSS and reserved fields.
> > 
> > This does not support automatic detection of a gzip compressed image.
> > 
> > Signed-off-by: Tom Rini <trini@ti.com>
> > 
> > ---
> > Changes in v1:
> > - Adopt to Mark Rutland's changes now in mainline kernel wrt text_offset
> >   / image_size
> > ---
> >  README             |    1 +
> >  common/cmd_bootm.c |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  include/bootm.h    |    2 +-
> >  3 files changed, 142 insertions(+), 1 deletion(-)
> > 
> > diff --git a/README b/README
> > index 1d71359..b9af7ac 100644
> > --- a/README
> > +++ b/README
> > @@ -959,6 +959,7 @@ The following options need to be configured:
> >  		CONFIG_CMD_BMP		* BMP support
> >  		CONFIG_CMD_BSP		* Board specific commands
> >  		CONFIG_CMD_BOOTD	  bootd
> > +		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
> >  		CONFIG_CMD_CACHE	* icache, dcache
> >  		CONFIG_CMD_CLK   	* clock command support
> >  		CONFIG_CMD_CONSOLE	  coninfo
> > diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
> > index 8b897c8d..843ec6e 100644
> > --- a/common/cmd_bootm.c
> > +++ b/common/cmd_bootm.c
> > @@ -627,3 +627,143 @@ U_BOOT_CMD(
> >  	"boot Linux zImage image from memory", bootz_help_text
> >  );
> >  #endif	/* CONFIG_CMD_BOOTZ */
> > +
> > +#ifdef CONFIG_CMD_BOOTI
> > +/* See Documentation/arm64/booting.txt in the Linux kernel */
> > +struct Image_header {
> > +	uint32_t	code0;		/* Executable code */
> > +	uint32_t	code1;		/* Executable code */
> > +	uint64_t	text_offset;	/* Image load offset, LE */
> > +	uint64_t	image_size;	/* Effective Image size, LE */
> > +	uint64_t	res1;		/* reserved */
> > +	uint64_t	res2;		/* reserved */
> > +	uint64_t	res3;		/* reserved */
> > +	uint64_t	res4;		/* reserved */
> > +	uint32_t	magic;		/* Magic number */
> > +	uint32_t	res5;
> > +};
> > +
> > +#define LINUX_ARM64_IMAGE_MAGIC	0x644d5241
> > +
> > +static int booti_setup(bootm_headers_t *images)
> > +{
> > +	struct Image_header *ih;
> > +	uint64_t dst;
> > +
> > +	ih = (struct Image_header *)map_sysmem(images->ep, 0);
> > +
> > +	if (ih->magic != le32_to_cpu(LINUX_ARM64_IMAGE_MAGIC)) {
> > +		puts("Bad Linux ARM64 Image magic!\n");
> > +		return 1;
> > +	}
> > +	
> > +	if (ih->image_size == 0) {
> > +		puts("Image lacks image_size field, assuming 16MiB\n");
> > +		ih->image_size = (16 << 20);
> > +	}
> 
> This should work for a defconfig, but it might be possible to build a
> larger kernel. From experiments with an allyesconfig, I can build a
> ~60MB kernel with ~20MB of uninitialised data after the end of the
> Image.

Part of me just wants to error out in this case.  Today people are
wrapping vmlinux up with a legacy header and making uImages.  My hope is
that with this and 3.17 we can encourage Image/Image.*/FIT Image usage
instead.  We could just as easily whack in 128MB, all the same.

> Modifying the Image feels a little dodgy, but I can't think of anything
> this would break.

Yeah.  In my mind, an Image without this information is the corner case,
not the normal case.  Doing it this way (a fixup to the data) means we
don't have to error check this twice or play some other games.

> > +	/*
> > +	 * If we are not at the correct run-time location, set the new
> > +	 * correct location and then move the image there.
> > +	 */
> > +	dst = gd->bd->bi_dram[0].start + le32_to_cpu(ih->text_offset);
> 
> This should be le64_to_cpu(ih->text_offset) to be strictly correct.
> 
> I wouldn't imagine we'd ever have a text_offset larger than 4GB, but it
> would be nice to keep things consistent with the documentation and
> kernel code.

Oh that's right, sixty-four bits is what we have...

> > +#ifdef CONFIG_SYS_LONGHELP
> > +static char booti_help_text[] =
> > +	"[addr [initrd[:size]] [fdt]]\n"
> > +	"    - boot Linux Image stored in memory\n"
> > +	"\tThe argument 'initrd' is optional and specifies the address\n"
> > +	"\tof the initrd in memory. The optional argument ':size' allows\n"
> > +	"\tspecifying the size of RAW initrd.\n"
> > +#if defined(CONFIG_OF_LIBFDT)
> > +	"\tSince booting a Linux kernelrequires a flat device-tree\n"
> 
> Nit: space between "kernel" and "requires"

Thanks.
Mark Rutland Aug. 15, 2014, 9:03 a.m. | #3
On Thu, Aug 14, 2014 at 08:11:49PM +0100, Tom Rini wrote:
> On Thu, Aug 14, 2014 at 04:16:50PM +0100, Mark Rutland wrote:
> > Hi Tom,
> > 
> > On Thu, Aug 14, 2014 at 11:42:36AM +0100, Tom Rini wrote:
> > > The default format for arm64 Linux kernels is the "Image" format,
> > > described in Documentation/arm64/booting.txt.  This, along with an
> > > optional gzip compression on top is all that is generated by default.
> > > The Image format has a magic number within the header for verification,
> > > a text_offset where the Image must be run from, an image_size that
> > > includes the BSS and reserved fields.
> > > 
> > > This does not support automatic detection of a gzip compressed image.
> > > 
> > > Signed-off-by: Tom Rini <trini@ti.com>
> > > 
> > > ---
> > > Changes in v1:
> > > - Adopt to Mark Rutland's changes now in mainline kernel wrt text_offset
> > >   / image_size
> > > ---
> > >  README             |    1 +
> > >  common/cmd_bootm.c |  140 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  include/bootm.h    |    2 +-
> > >  3 files changed, 142 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/README b/README
> > > index 1d71359..b9af7ac 100644
> > > --- a/README
> > > +++ b/README
> > > @@ -959,6 +959,7 @@ The following options need to be configured:
> > >  		CONFIG_CMD_BMP		* BMP support
> > >  		CONFIG_CMD_BSP		* Board specific commands
> > >  		CONFIG_CMD_BOOTD	  bootd
> > > +		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
> > >  		CONFIG_CMD_CACHE	* icache, dcache
> > >  		CONFIG_CMD_CLK   	* clock command support
> > >  		CONFIG_CMD_CONSOLE	  coninfo
> > > diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
> > > index 8b897c8d..843ec6e 100644
> > > --- a/common/cmd_bootm.c
> > > +++ b/common/cmd_bootm.c
> > > @@ -627,3 +627,143 @@ U_BOOT_CMD(
> > >  	"boot Linux zImage image from memory", bootz_help_text
> > >  );
> > >  #endif	/* CONFIG_CMD_BOOTZ */
> > > +
> > > +#ifdef CONFIG_CMD_BOOTI
> > > +/* See Documentation/arm64/booting.txt in the Linux kernel */
> > > +struct Image_header {
> > > +	uint32_t	code0;		/* Executable code */
> > > +	uint32_t	code1;		/* Executable code */
> > > +	uint64_t	text_offset;	/* Image load offset, LE */
> > > +	uint64_t	image_size;	/* Effective Image size, LE */
> > > +	uint64_t	res1;		/* reserved */
> > > +	uint64_t	res2;		/* reserved */
> > > +	uint64_t	res3;		/* reserved */
> > > +	uint64_t	res4;		/* reserved */
> > > +	uint32_t	magic;		/* Magic number */
> > > +	uint32_t	res5;
> > > +};
> > > +
> > > +#define LINUX_ARM64_IMAGE_MAGIC	0x644d5241
> > > +
> > > +static int booti_setup(bootm_headers_t *images)
> > > +{
> > > +	struct Image_header *ih;
> > > +	uint64_t dst;
> > > +
> > > +	ih = (struct Image_header *)map_sysmem(images->ep, 0);
> > > +
> > > +	if (ih->magic != le32_to_cpu(LINUX_ARM64_IMAGE_MAGIC)) {
> > > +		puts("Bad Linux ARM64 Image magic!\n");
> > > +		return 1;
> > > +	}
> > > +	
> > > +	if (ih->image_size == 0) {
> > > +		puts("Image lacks image_size field, assuming 16MiB\n");
> > > +		ih->image_size = (16 << 20);
> > > +	}
> > 
> > This should work for a defconfig, but it might be possible to build a
> > larger kernel. From experiments with an allyesconfig, I can build a
> > ~60MB kernel with ~20MB of uninitialised data after the end of the
> > Image.
> 
> Part of me just wants to error out in this case.  Today people are
> wrapping vmlinux up with a legacy header and making uImages.  My hope is
> that with this and 3.17 we can encourage Image/Image.*/FIT Image usage
> instead.  We could just as easily whack in 128MB, all the same.

Sure, it's unlikely that someone will build that big a (< v3.17) kernel
for reasons other than breaking things. I just thought I should mention
in case this crops up again.
 
> > Modifying the Image feels a little dodgy, but I can't think of anything
> > this would break.
> 
> Yeah.  In my mind, an Image without this information is the corner case,
> not the normal case.  Doing it this way (a fixup to the data) means we
> don't have to error check this twice or play some other games.

Ok. As I said I can't think of anything this should break. This should
only affect older kernels so shouldn't be a problem going forward.

Prior to v3.17 you'll also find the text_offset field could be in an
arbitrary endianness, though should always have value 0x80000. So if you
want to boot BE (< v3.17) kernels you'd have to fix that up too. Post
v3.17 it's subject to randomization.

Cheers,
Mark.
Tom Rini Aug. 30, 2014, 3:15 p.m. | #4
On Thu, Aug 14, 2014 at 06:42:36AM -0400, Tom Rini wrote:

> The default format for arm64 Linux kernels is the "Image" format,
> described in Documentation/arm64/booting.txt.  This, along with an
> optional gzip compression on top is all that is generated by default.
> The Image format has a magic number within the header for verification,
> a text_offset where the Image must be run from, an image_size that
> includes the BSS and reserved fields.
> 
> This does not support automatic detection of a gzip compressed image.
> 
> Signed-off-by: Tom Rini <trini@ti.com>

Applied to u-boot/master, thanks!

Patch

diff --git a/README b/README
index 1d71359..b9af7ac 100644
--- a/README
+++ b/README
@@ -959,6 +959,7 @@  The following options need to be configured:
 		CONFIG_CMD_BMP		* BMP support
 		CONFIG_CMD_BSP		* Board specific commands
 		CONFIG_CMD_BOOTD	  bootd
+		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
 		CONFIG_CMD_CACHE	* icache, dcache
 		CONFIG_CMD_CLK   	* clock command support
 		CONFIG_CMD_CONSOLE	  coninfo
diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
index 8b897c8d..843ec6e 100644
--- a/common/cmd_bootm.c
+++ b/common/cmd_bootm.c
@@ -627,3 +627,143 @@  U_BOOT_CMD(
 	"boot Linux zImage image from memory", bootz_help_text
 );
 #endif	/* CONFIG_CMD_BOOTZ */
+
+#ifdef CONFIG_CMD_BOOTI
+/* See Documentation/arm64/booting.txt in the Linux kernel */
+struct Image_header {
+	uint32_t	code0;		/* Executable code */
+	uint32_t	code1;		/* Executable code */
+	uint64_t	text_offset;	/* Image load offset, LE */
+	uint64_t	image_size;	/* Effective Image size, LE */
+	uint64_t	res1;		/* reserved */
+	uint64_t	res2;		/* reserved */
+	uint64_t	res3;		/* reserved */
+	uint64_t	res4;		/* reserved */
+	uint32_t	magic;		/* Magic number */
+	uint32_t	res5;
+};
+
+#define LINUX_ARM64_IMAGE_MAGIC	0x644d5241
+
+static int booti_setup(bootm_headers_t *images)
+{
+	struct Image_header *ih;
+	uint64_t dst;
+
+	ih = (struct Image_header *)map_sysmem(images->ep, 0);
+
+	if (ih->magic != le32_to_cpu(LINUX_ARM64_IMAGE_MAGIC)) {
+		puts("Bad Linux ARM64 Image magic!\n");
+		return 1;
+	}
+	
+	if (ih->image_size == 0) {
+		puts("Image lacks image_size field, assuming 16MiB\n");
+		ih->image_size = (16 << 20);
+	}
+
+	/*
+	 * If we are not at the correct run-time location, set the new
+	 * correct location and then move the image there.
+	 */
+	dst = gd->bd->bi_dram[0].start + le32_to_cpu(ih->text_offset);
+	if (images->ep != dst) {
+		void *src;
+
+		debug("Moving Image from 0x%lx to 0x%llx\n", images->ep, dst);
+
+		src = (void *)images->ep;
+		images->ep = dst;
+		memmove((void *)dst, src, le32_to_cpu(ih->image_size));
+	}
+
+	return 0;
+}
+
+/*
+ * Image booting support
+ */
+static int booti_start(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[], bootm_headers_t *images)
+{
+	int ret;
+	struct Image_header *ih;
+
+	ret = do_bootm_states(cmdtp, flag, argc, argv, BOOTM_STATE_START,
+			      images, 1);
+
+	/* Setup Linux kernel Image entry point */
+	if (!argc) {
+		images->ep = load_addr;
+		debug("*  kernel: default image load address = 0x%08lx\n",
+				load_addr);
+	} else {
+		images->ep = simple_strtoul(argv[0], NULL, 16);
+		debug("*  kernel: cmdline image address = 0x%08lx\n",
+			images->ep);
+	}
+
+	ret = booti_setup(images);
+	if (ret != 0)
+		return 1;
+
+	ih = (struct Image_header *)map_sysmem(images->ep, 0);
+
+	lmb_reserve(&images->lmb, images->ep, le32_to_cpu(ih->image_size));
+
+	/*
+	 * Handle the BOOTM_STATE_FINDOTHER state ourselves as we do not
+	 * have a header that provide this informaiton.
+	 */
+	if (bootm_find_ramdisk_fdt(flag, argc, argv))
+		return 1;
+
+	return 0;
+}
+
+int do_booti(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	int ret;
+
+	/* Consume 'booti' */
+	argc--; argv++;
+
+	if (booti_start(cmdtp, flag, argc, argv, &images))
+		return 1;
+
+	/*
+	 * We are doing the BOOTM_STATE_LOADOS state ourselves, so must
+	 * disable interrupts ourselves
+	 */
+	bootm_disable_interrupts();
+
+	images.os.os = IH_OS_LINUX;
+	ret = do_bootm_states(cmdtp, flag, argc, argv,
+			      BOOTM_STATE_OS_PREP | BOOTM_STATE_OS_FAKE_GO |
+			      BOOTM_STATE_OS_GO,
+			      &images, 1);
+
+	return ret;
+}
+
+#ifdef CONFIG_SYS_LONGHELP
+static char booti_help_text[] =
+	"[addr [initrd[:size]] [fdt]]\n"
+	"    - boot Linux Image stored in memory\n"
+	"\tThe argument 'initrd' is optional and specifies the address\n"
+	"\tof the initrd in memory. The optional argument ':size' allows\n"
+	"\tspecifying the size of RAW initrd.\n"
+#if defined(CONFIG_OF_LIBFDT)
+	"\tSince booting a Linux kernelrequires a flat device-tree\n"
+	"\ta third argument is required which is the address of the\n"
+	"\tdevice-tree blob. To boot that kernel without an initrd image,\n"
+	"\tuse a '-' for the second argument.\n"
+#endif
+	"";
+#endif
+
+U_BOOT_CMD(
+	booti,	CONFIG_SYS_MAXARGS,	1,	do_booti,
+	"boot arm64 Linux Image image from memory", booti_help_text
+);
+#endif	/* CONFIG_CMD_BOOTI */
diff --git a/include/bootm.h b/include/bootm.h
index 4a308d8..694d6fc 100644
--- a/include/bootm.h
+++ b/include/bootm.h
@@ -48,7 +48,7 @@  int boot_selected_os(int argc, char * const argv[], int state,
 
 ulong bootm_disable_interrupts(void);
 
-/* This is a special function used by bootz */
+/* This is a special function used by booti/bootz */
 int bootm_find_ramdisk_fdt(int flag, int argc, char * const argv[]);
 
 int do_bootm_states(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],