Re: [U-Boot] [RFC PATCH] arm: bootm: Boot kernel with U-Boot's FDT blob

On Wednesday 11 January 2017 12:50 PM, Michal Simek wrote:

On 11.1.2017 06:19, Lokesh Vutla wrote:

...

On Tuesday 10 January 2017 06:28 PM, Michal Simek wrote:

...

U-Boot configured via DTB can use the same DTB for booting the kernel. When OF_CONTROL is used fdtcontroladdr is setup and can be use for boot.

Signed-off-by: Michal Simek michal.simek@xilinx.com

Didn't check if there is any side effect or not but it looks weird when you have DT driver u-boot that you have to load dtb again.

---

arch/arm/lib/bootm.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)

diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c index 43cc83ec95b6..9740045b0094 100644 --- a/arch/arm/lib/bootm.c +++ b/arch/arm/lib/bootm.c @@ -245,6 +245,20 @@ static void boot_prep_linux(bootm_headers_t *images) } setup_board_tags(&params); setup_end_tag(gd->bd);

• } else if (IS_ENABLED(CONFIG_OF_CONTROL)) {

+#ifdef CONFIG_OF_LIBFDT

• images->ft_addr = (char *)getenv_hex("fdtcontroladdr", 0);
  

If your intent is to use U-Boot's fdt as fallback, why can't we just use gd->fdt_blob instead of getting from env?

Not an issue to use gd->fdt_block instead but I expect we should copy it to the different location too.

...

IMO, this is not the right place to get the fallback fdt. Instead it should fallback at bootm_get_fdt() so that other parameters like images->ft_length is also updated. Can you try the following diff?

Not a problem to move it to this position.

I have tried it and system is not booting.

Hmm.. not sure if I am missing something. I am able to boot with this change and not loading any dtb: http://pastebin.ubuntu.com/23780811/

Thanks and regards, Lokesh

...

diff --git a/common/image-fdt.c b/common/image-fdt.c index e7540be8d6..f8714b3702 100644 --- a/common/image-fdt.c +++ b/common/image-fdt.c @@ -238,7 +238,6 @@ int boot_get_fdt(int flag, int argc, char * const argv[], uint8_t arch, int fdt_noffset; #endif const char *select = NULL;

• int ok_no_fdt = 0;

  *of_flat_tree = NULL; *of_size = 0;

@@ -311,7 +310,7 @@ int boot_get_fdt(int flag, int argc, char * const argv[], uint8_t arch, fdt_addr); fdt_hdr = image_get_fdt(fdt_addr); if (!fdt_hdr)

• 		goto no_fdt;
  

• 		goto fallback_fdt;
  
  /*
   * move image data to the load address,
  

@@ -381,7 +380,7 @@ int boot_get_fdt(int flag, int argc, char * const argv[], uint8_t arch, break; default: puts("ERROR: Did not find a cmdline Flattened Device Tree\n");

This probably requires some code around not to show this error message because it should be valid boot option.

...

• 	goto no_fdt;
  

• 	goto fallback_fdt;
  

  }

  printf(" Booting using the fdt blob at %#08lx\n", fdt_addr);

@@ -415,11 +414,17 @@ int boot_get_fdt(int flag, int argc, char * const argv[], uint8_t arch, } } else { debug("## No Flattened Device Tree\n");

• 	goto no_fdt;
  

• 	goto fallback_fdt;
  

  } } else { debug("## No Flattened Device Tree\n");

• goto no_fdt;
  

• goto fallback_fdt;
  

• }

+fallback_fdt:

• if (!fdt_blob) {

• printf("## Using U-boot's fdt to boot kernel\n");
  

• fdt_blob = (char *)gd->fdt_blob;
  

  }

  *of_flat_tree = fdt_blob;

@@ -429,12 +434,10 @@ int boot_get_fdt(int flag, int argc, char * const argv[], uint8_t arch,

return 0;

-no_fdt:

• ok_no_fdt = 1;

error: *of_flat_tree = NULL; *of_size = 0;

• if (!select && ok_no_fdt) {

• if (!select) { debug("Continuing to boot without FDT\n"); return 0; }

Thanks and regards, Lokesh

Thanks, Michal