Hi Alexandru,
On Fri, 12 Mar 2021 at 10:32, Alexandru Gagniuc mr.nuke.me@gmail.com wrote:
U-Boot expects the FDT to be located right after the _end linker symbol (see fdtdec.c: board_fdt_blob_setup())
The "basic" LOAD_FIT path is aware of this limitation, and relocates the FDT at the expected location. Guessing the expected location probably only works reliably on 32-bit arm, and it feels like a hack. One proposal would be to pass the FDT address to u-boot (e.g. using 'r2' on arm platforms).
We could do that, but the current behaviour is OK. It is required that you can joined U-Boot and its FDT and get a valid image.
The variable is named "fdt_hack" to remind future contributors that, "hey! we should fix the underlying problem". However, that is beyond the scope of this patch.
I think it is fine to require it be after U-Boot, in fact that is defined by U-Boot. So I don't think you need to think of it as a hack.
Signed-off-by: Alexandru Gagniuc mr.nuke.me@gmail.com
common/spl/spl.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/common/spl/spl.c b/common/spl/spl.c index 8f6c8dba6f..e63f05bb33 100644 --- a/common/spl/spl.c +++ b/common/spl/spl.c @@ -201,6 +201,7 @@ static int spl_load_fit_image(struct spl_image_info *spl_image, { bootm_headers_t images; const char *fit_uname_config = NULL;
uintptr_t fdt_hack; const char *uname; ulong fw_data = 0, dt_data = 0, img_data = 0; ulong fw_len = 0, dt_len = 0, img_len = 0;@@ -233,9 +234,18 @@ static int spl_load_fit_image(struct spl_image_info *spl_image, ret = fit_image_load(&images, (ulong)header, NULL, &fit_uname_config, IH_ARCH_DEFAULT, IH_TYPE_FLATDT, -1, FIT_LOAD_OPTIONAL, &dt_data, &dt_len);
if (ret >= 0)
if (ret >= 0) { spl_image->fdt_addr = (void *)dt_data;if (spl_image->os == IH_OS_U_BOOT) {/* HACK: U-boot expects FDT at a specific address */fdt_hack = spl_image->load_addr + spl_image->size;fdt_hack = (fdt_hack + 3) & ~3;
I don't think this is needed and it just confuses things. If U-Boot is not an aligned sign, it can't boot because the DT ends up in the wrong place. The build system makes sure this doesn't happen.
debug("Relocating FDT to %p\n", spl_image->fdt_addr);memcpy((void *)fdt_hack, spl_image->fdt_addr, dt_len);}}conf_noffset = fit_conf_get_node((const void *)header, fit_uname_config); if (conf_noffset <= 0)-- 2.26.2
Regards, Simon