On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <[email protected]> wrote:
>
> Adding the -@ switch to dtc results in the binary devicetrees containing
> a list of symbolic references and their paths. This is necessary to
> apply device tree overlays e.g. on Raspberry Pi as described on
> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>
> Obviously the downside of this change is an increas of the size of the
> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>
> $ du -s arch/arm/boot/dts*
> 101380 arch/arm/boot/dts-pre
> 114308 arch/arm/boot/dts-post
>
> so this is in average an increase of 12.8% in size.
>
> Signed-off-by: Uwe Kleine-König <[email protected]>
(CCing DT ML.)
https://www.spinics.net/lists/linux-kbuild/msg27904.html
See Rob's comment:
"We've already rejected doing that. Turning on '-@' can grow the dtb
size by a significant amount which could be problematic for some
boards."
> ---
> scripts/Makefile.lib | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 213677a5ed33..0683a5808f7f 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -319,7 +319,7 @@ $(obj)/%.dtb.S: $(obj)/%.dtb FORCE
>
> quiet_cmd_dtc = DTC $@
> cmd_dtc = $(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
> - $(DTC) -O $(patsubst .%,%,$(suffix $@)) -o $@ -b 0 \
> + $(DTC) -@ -O $(patsubst .%,%,$(suffix $@)) -o $@ -b 0 \
> $(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
> -d $(depfile).dtc.tmp $(dtc-tmp) ; \
> cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
> --
> 2.29.2
>
--
Best Regards
Masahiro Yamada
Hello Masahiro,
On 1/25/21 10:53 PM, Masahiro Yamada wrote:
> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <[email protected]> wrote:
>>
>> Adding the -@ switch to dtc results in the binary devicetrees containing
>> a list of symbolic references and their paths. This is necessary to
>> apply device tree overlays e.g. on Raspberry Pi as described on
>> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>>
>> Obviously the downside of this change is an increas of the size of the
>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>>
>> $ du -s arch/arm/boot/dts*
>> 101380 arch/arm/boot/dts-pre
>> 114308 arch/arm/boot/dts-post
>>
>> so this is in average an increase of 12.8% in size.
>>
>> Signed-off-by: Uwe Kleine-König <[email protected]>
>
>
> (CCing DT ML.)
makes sense, thanks.
> https://www.spinics.net/lists/linux-kbuild/msg27904.html
>
> See Rob's comment:
>
> "We've already rejected doing that. Turning on '-@' can grow the dtb
> size by a significant amount which could be problematic for some
> boards."
The patch was created after some conversation on irc which continued
after I sent the patch. I added the participating parties to Cc:.
The (relevant) followups were:
Geert suggested to always generate the symbols and provide a way to
strip the symbols for installation if and when they are not needed.
Rob said: "I'm less concerned with the size increases, but rather that
labels go from purely source syntax to an ABI. I'd rather see some
decision as to which labels are enabled or not."
And then I learned with hints from Rob and Geert that symbols are not
really necessary for overlays, you just cannot use named labels. But
using
target-path = "/soc/i2c@23473245";
or
target = <&{/soc/i2c@23473245}>;
instead of
target = <&i2c1>;
works fine. (And if you need to add a phandle the &{/path/to/node}
construct should work, too (but I didn't test).) Using labels is a tad
nicer, but the problem I wanted to address with my patch now has a known
different solution.
Best regards
Uwe
Hi Uwe,
On Tue, Jan 26, 2021 at 8:21 AM Uwe Kleine-König <[email protected]> wrote:
> And then I learned with hints from Rob and Geert that symbols are not
> really necessary for overlays, you just cannot use named labels. But
> using
>
> target-path = "/soc/i2c@23473245";
>
> or
>
> target = <&{/soc/i2c@23473245}>;
>
> instead of
>
> target = <&i2c1>;
>
> works fine. (And if you need to add a phandle the &{/path/to/node}
> construct should work, too (but I didn't test).) Using labels is a tad
> nicer, but the problem I wanted to address with my patch now has a known
> different solution.
Please don't use "target" and "target-path". Since the introduction of
sugar syntax support in v4.15[1], you can just use "&label", like in a normal
DTS file. Paths do need the special "&{/path/to/node}" syntax instead
of "/path/to/node", though.
As usual, you can find lots of examples of DT overlays in my repo[2].
[1] commit 4201d057ea91c3d6 ("scripts/dtc: Update to upstream version
v1.4.5-3-gb1a60033c110")
[2] https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/renesas-overlays
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
+frank
On 1/26/21 2:43 AM, Geert Uytterhoeven wrote:
> Hi Uwe,
>
> On Tue, Jan 26, 2021 at 8:21 AM Uwe Kleine-König <[email protected]> wrote:
>> And then I learned with hints from Rob and Geert that symbols are not
>> really necessary for overlays, you just cannot use named labels. But
>> using
>>
>> target-path = "/soc/i2c@23473245";
>>
>> or
>>
>> target = <&{/soc/i2c@23473245}>;
>>
>> instead of
>>
>> target = <&i2c1>;
>>
>> works fine. (And if you need to add a phandle the &{/path/to/node}
>> construct should work, too (but I didn't test).) Using labels is a tad
>> nicer, but the problem I wanted to address with my patch now has a known
>> different solution.
>
> Please don't use "target" and "target-path". Since the introduction of
> sugar syntax support in v4.15[1], you can just use "&label", like in a normal
> DTS file. Paths do need the special "&{/path/to/node}" syntax instead
> of "/path/to/node", though.
>
> As usual, you can find lots of examples of DT overlays in my repo[2].
>
> [1] commit 4201d057ea91c3d6 ("scripts/dtc: Update to upstream version
> v1.4.5-3-gb1a60033c110")
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/renesas-overlays
>
> Gr{oetje,eeting}s,
>
> Geert
>
+frank
On 1/26/21 1:20 AM, Uwe Kleine-König wrote:
> Hello Masahiro,
>
> On 1/25/21 10:53 PM, Masahiro Yamada wrote:
>> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <[email protected]> wrote:
>>>
>>> Adding the -@ switch to dtc results in the binary devicetrees containing
>>> a list of symbolic references and their paths. This is necessary to
>>> apply device tree overlays e.g. on Raspberry Pi as described on
>>> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>>>
>>> Obviously the downside of this change is an increas of the size of the
>>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>>>
>>> $ du -s arch/arm/boot/dts*
>>> 101380 arch/arm/boot/dts-pre
>>> 114308 arch/arm/boot/dts-post
>>>
>>> so this is in average an increase of 12.8% in size.
>>>
>>> Signed-off-by: Uwe Kleine-König <[email protected]>
>>
>>
>> (CCing DT ML.)
>
> makes sense, thanks.
>
>> https://www.spinics.net/lists/linux-kbuild/msg27904.html
>>
>> See Rob's comment:
>>
>> "We've already rejected doing that. Turning on '-@' can grow the dtb
>> size by a significant amount which could be problematic for some
>> boards."
>
> The patch was created after some conversation on irc which continued
> after I sent the patch. I added the participating parties to Cc:.
>
> The (relevant) followups were:
>
> Geert suggested to always generate the symbols and provide a way to
> strip the symbols for installation if and when they are not needed.
>
> Rob said: "I'm less concerned with the size increases, but rather that
> labels go from purely source syntax to an ABI. I'd rather see some
> decision as to which labels are enabled or not."
>
> And then I learned with hints from Rob and Geert that symbols are not
> really necessary for overlays, you just cannot use named labels. But
> using
>
> target-path = "/soc/i2c@23473245";
>
> or
>
> target = <&{/soc/i2c@23473245}>;
>
> instead of
>
> target = <&i2c1>;
>
> works fine. (And if you need to add a phandle the &{/path/to/node}
> construct should work, too (but I didn't test).) Using labels is a tad nicer, but the problem I wanted to address with my patch now has a known different solution.
>
> Best regards
> Uwe
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
+frank
On 1/25/21 3:53 PM, Masahiro Yamada wrote:
> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <[email protected]> wrote:
>>
>> Adding the -@ switch to dtc results in the binary devicetrees containing
>> a list of symbolic references and their paths. This is necessary to
>> apply device tree overlays e.g. on Raspberry Pi as described on
>> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>>
>> Obviously the downside of this change is an increas of the size of the
>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>>
>> $ du -s arch/arm/boot/dts*
>> 101380 arch/arm/boot/dts-pre
>> 114308 arch/arm/boot/dts-post
>>
>> so this is in average an increase of 12.8% in size.
>>
>> Signed-off-by: Uwe Kleine-König <[email protected]>
>
>
> (CCing DT ML.)
>
>
> https://www.spinics.net/lists/linux-kbuild/msg27904.html
>
> See Rob's comment:
>
> "We've already rejected doing that. Turning on '-@' can grow the dtb
> size by a significant amount which could be problematic for some
> boards."
>
>
>
>
>
>
>
>
>> ---
>> scripts/Makefile.lib | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
>> index 213677a5ed33..0683a5808f7f 100644
>> --- a/scripts/Makefile.lib
>> +++ b/scripts/Makefile.lib
>> @@ -319,7 +319,7 @@ $(obj)/%.dtb.S: $(obj)/%.dtb FORCE
>>
>> quiet_cmd_dtc = DTC $@
>> cmd_dtc = $(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
>> - $(DTC) -O $(patsubst .%,%,$(suffix $@)) -o $@ -b 0 \
>> + $(DTC) -@ -O $(patsubst .%,%,$(suffix $@)) -o $@ -b 0 \
>> $(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
>> -d $(depfile).dtc.tmp $(dtc-tmp) ; \
>> cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
>> --
>> 2.29.2
>>
>
>
> --
> Best Regards
>
> Masahiro Yamada
>
Hi Uwe,
On 1/26/21 12:03 PM, Frank Rowand wrote:
> +frank
>
> On 1/26/21 1:20 AM, Uwe Kleine-König wrote:
>> Hello Masahiro,
>>
>> On 1/25/21 10:53 PM, Masahiro Yamada wrote:
>>> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <[email protected]> wrote:
>>>>
>>>> Adding the -@ switch to dtc results in the binary devicetrees containing
>>>> a list of symbolic references and their paths. This is necessary to
>>>> apply device tree overlays e.g. on Raspberry Pi as described on
>>>> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>>>>
>>>> Obviously the downside of this change is an increas of the size of the
>>>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>>>>
>>>> $ du -s arch/arm/boot/dts*
>>>> 101380 arch/arm/boot/dts-pre
>>>> 114308 arch/arm/boot/dts-post
>>>>
>>>> so this is in average an increase of 12.8% in size.
>>>>
>>>> Signed-off-by: Uwe Kleine-König <[email protected]>
>>>
>>>
>>> (CCing DT ML.)
>>
>> makes sense, thanks.
>>
>>> https://www.spinics.net/lists/linux-kbuild/msg27904.html
>>>
>>> See Rob's comment:
>>>
>>> "We've already rejected doing that. Turning on '-@' can grow the dtb
>>> size by a significant amount which could be problematic for some
>>> boards."
>>
>> The patch was created after some conversation on irc which continued
>> after I sent the patch. I added the participating parties to Cc:.
Unfortunately I have not been on irc recently (now rectified). Do you
perchance have a copy of the irc conversation that you can send me?
(No need to edit out unrelated messages, a simple cut and paste from
the start of the conversation to the end is fine.)
-Frank
>>
>> The (relevant) followups were:
>>
>> Geert suggested to always generate the symbols and provide a way to
>> strip the symbols for installation if and when they are not needed.
>>
>> Rob said: "I'm less concerned with the size increases, but rather that
>> labels go from purely source syntax to an ABI. I'd rather see some
>> decision as to which labels are enabled or not."
>>
>> And then I learned with hints from Rob and Geert that symbols are not
>> really necessary for overlays, you just cannot use named labels. But
>> using
>>
>> target-path = "/soc/i2c@23473245";
>>
>> or
>>
>> target = <&{/soc/i2c@23473245}>;
>>
>> instead of
>>
>> target = <&i2c1>;
>>
>> works fine. (And if you need to add a phandle the &{/path/to/node}
>> construct should work, too (but I didn't test).) Using labels is a tad nicer, but the problem I wanted to address with my patch now has a known different solution.
>>
>> Best regards
>> Uwe
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> [email protected]
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>