Hi Simon,
On 2023/06/19 21:36, Simon Glass wrote:
Hi Kunihiko,
On Fri, 16 Jun 2023 at 00:59, Kunihiko Hayashi hayashi.kunihiko@socionext.com wrote:
Hi Simon,
Thank you for your comment.
On 2023/06/13 6:17, Simon Glass wrote:
Hi Kunihiko,
On Thu, 8 Jun 2023 at 07:53, Kunihiko Hayashi hayashi.kunihiko@socionext.com wrote:
There are cases that the devicetree blob is placed after _end, such as fdt_find_separate() returns _end. This is in bss area cleared before relocation.
When GD_FLG_SKIP_RELOC is set, the blob is still in bss, but will be cleared. As a result, the devicetree become invalid.
To avoid this issue, should relocate it to the new fdt area using the latter condition in reloc_fdt().
Signed-off-by: Kunihiko Hayashi hayashi.kunihiko@socionext.com
common/board_f.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/common/board_f.c b/common/board_f.c index 51d2f3c365e9..9a245872d190 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -622,7 +622,8 @@ static int init_post(void) static int reloc_fdt(void) { if (!IS_ENABLED(CONFIG_OF_EMBED)) {
if (gd->flags & GD_FLG_SKIP_RELOC)
if (gd->flags & GD_FLG_SKIP_RELOC &&gd->fdt_blob != &_end)!IS_ENABLED(CONFIG_OF_EMBED) == IS_ENABLED(CONFIG_OF_SEPARATE)
reloc_fdt() is only called by U-Boot (not SP)
So the FDT was found by fdt_find_separate() and gd->fdt_blob == &_end
So, is there any case where:
gd->flags & GD_FLG_SKIP_RELO is true gd->fdt_blob != &_end is true
?
Yes. But in fact, if (gd->flags & GD_FLG_SKIP_RELOC is true) and (gd->fdt_blob overlaps .bss section), the fdt should be relocated because clear_bss() will clear the fdt after that.
I misstated my point. I am wondering if gd(->fdt_blob != &_end) is ever false? If not, then we can always relocate.
When CONFIG_OF_SEPARATE is true, it seems that (gd->fdt_blob != &_end) is always false because the fdt file is concatinated to the end of the image file in Makefile.
I can't think of one.
If that is the case, then you could add a comment to this effect and unconditionally relocate if !CONFIG_OF_EMBED.
I'm not sure if it is possible to unconditionally relocate the fdt, I think we need to know if the fdt overlaps .bss section.
What is the down-side of always relocating, and when would the fdt not overlap the .bss section?
The fdt always overlaps the .bss section, so it should be relocated even if (gd->flags & GL_FLG_SKIP_RELOC) is true.
Note that OF_EMBED is not to be used in production boards. That is violated by a few things at present, but IMO always relocating should be safe.
Yes, I undestand. I delete the condition in v2, and change to always relocate the fdt in case of !OF_EMBED.
Thank you,
--- Best Regards Kunihiko Hayashi