At present in SPL we place the device tree immediately after BSS. This avoids needing to copy it out of the way before BSS can be used. However on some boards BSS is not placed with the image - e.g. it can be in RAM if available.
Add an option to tell U-Boot that the device tree should be placed at the end of the image binary (_image_binary_end) instead of at the end of BSS.
Note: A common reason to place BSS in RAM is to support the FAT filesystem. We should update the code so that it does not use so much BSS.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v2: None
Kconfig | 10 ++++++++++ include/asm-generic/sections.h | 1 + lib/fdtdec.c | 7 +++++-- 3 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/Kconfig b/Kconfig index f364a7a..01c6977 100644 --- a/Kconfig +++ b/Kconfig @@ -132,6 +132,16 @@ config SPL_STACK_R_ADDR Specify the address in SDRAM for the SPL stack. This will be set up before board_init_r() is called.
+config SPL_SEPARATE_BSS + depends on SPL + bool "BSS section is in a different memory region from text" + help + Some platforms need a large BSS region in SPL and can provide this + because RAM is already set up. In this case BSS can be moved to RAM. + This option should then be enabled so that the correct device tree + location is used. Normally we put the device tree at the end of BSS + but with this option enabled, it goes at _image_binary_end. + config TPL bool depends on SPL && SUPPORT_TPL diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index 458952f..328bc62 100644 --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -71,6 +71,7 @@ extern char __bss_start[]; extern char __bss_end[]; extern char __image_copy_start[]; extern char __image_copy_end[]; +extern char _image_binary_end[]; extern char __rel_dyn_start[]; extern char __rel_dyn_end[];
diff --git a/lib/fdtdec.c b/lib/fdtdec.c index 1749468..4684496 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -1222,8 +1222,11 @@ int fdtdec_setup(void) gd->fdt_blob = __dtb_dt_begin; # elif defined CONFIG_OF_SEPARATE # ifdef CONFIG_SPL_BUILD - /* FDT is at end of BSS */ - gd->fdt_blob = (ulong *)&__bss_end; + /* FDT is at end of BSS unless it is in a different memory region */ + if (IS_ENABLED(CONFIG_SPL_SEPARATE_BSS)) + gd->fdt_blob = (ulong *)&_image_binary_end; + else + gd->fdt_blob = (ulong *)&__bss_end; # else /* FDT is at end of image */ gd->fdt_blob = (ulong *)&_end;