For static DT usecases, we don't need the disabled nodes and can skip unflattening. This saves a significant amount of RAM in memory constrained cases. In one example on STM32F469, the RAM usage goes from 118K to 26K.
There are a few cases in the kernel that modify the status property dynamically. These all are changes from enabled to disabled, depend on OF_DYNAMIC or are not FDT based (PDT based). Cc: Nicolas Pitre <nicolas.pi...@linaro.org> Cc: Frank Rowand <frowand.l...@gmail.com> Signed-off-by: Rob Herring <r...@kernel.org> --- For more background, see this presentation from Nico: https://connect.linaro.org/resource/sfo17/sfo17-100/ drivers/of/fdt.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index f8c39705418b..efe91c6856a0 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -396,6 +396,10 @@ static int unflatten_dt_nodes(const void *blob, if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH)) continue; + if (!IS_ENABLED(CONFIG_OF_DYNAMIC) && + !of_fdt_device_is_available(blob, offset)) + continue; + if (!populate_node(blob, offset, &mem, nps[depth], &nps[depth+1], dryrun)) return mem - base; -- 2.11.0
