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 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.
Of course the down size is that you would probably rather relocate it to just after BSS (rather than to the top of memory) but it doesn't much matter, I suspect.
Thank you,
--- Best Regards Kunihiko Hayashi