Hi Kunihiko, On Fri, 16 Jun 2023 at 00:59, Kunihiko Hayashi <[email protected]> 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 > > <[email protected]> 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 <[email protected]> > >> --- > >> 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. > > > 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? 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. > > > 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, Regards, Simon
