[PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[Suraj Kakade]

cmd_dtc inlines dtc_cpp_flags (including every upstream dtsi -I
path) in the HOSTCC command. With a long $(srctree) that command is
too large for /bin/sh -c and Make fails with "Argument list too
long" while building a .dtb.

Write the flags to a per-target .dtc.flags.tmp file and pass @file to
HOSTCC/CPP so the shell command stays short.

This change requires GNU Make >= 4.0, since $(file ...) is not
supported by Make 3.x.

Fixes: d31ff219a833 ("Makefile.lib: find capsule ESL dtsi file with CONFIG_OF_UPSTREAM")
Fixes: 1e7883f6325a ("dtbo: Fix dtbo generation rules")
Signed-off-by: Suraj Kakade <suraj.hanumantkakade@amd.com>
---
 scripts/Makefile.lib | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 24b1a581790..6066abed199 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -448,7 +448,8 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 	(cat $< > $(pre-tmp)); \
 	$(foreach f,$(subst $(quote),,$(dtsi_include_list) $(CONFIG_DEVICE_TREE_INCLUDES)), \
 	  echo '$(pound)include "$(f)"' >> $(pre-tmp);) \
-	$(HOSTCC) -E $(dtc_cpp_flags) -I$(obj) -x assembler-with-cpp -o $(dtc-tmp) $(pre-tmp) ; \
+	$(file >$(dtc-flags-tmp),$(dtc_cpp_flags) -I$(obj)) \
+	$(HOSTCC) -E @$(dtc-flags-tmp) -x assembler-with-cpp -o $(dtc-tmp) $(pre-tmp) ; \
 	$(DTC) -O dtb -o $@ -b 0 \
 		-i $(dir $<) -i $(u_boot_dtsi_loc) $(DTC_FLAGS) \
 		-d $(depfile).dtc.tmp $(dtc-tmp) || \
@@ -477,6 +478,7 @@ $(obj)/%.dtb: $(src)/%.dts $(DTC) $(dtsi_include_list_deps) $(DT_TMP_SCHEMA) FOR
 
 pre-tmp = $(subst $(comma),_,$(dot-target).pre.tmp)
 dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
+dtc-flags-tmp = $(subst $(comma),_,$(dot-target).dtc.flags.tmp)
 
 # DTCO
 # ---------------------------------------------------------------------------
@@ -486,7 +488,8 @@ quiet_cmd_dtco = DTCO    $@
 # No generation of assembly file either
 # Modified for U-Boot
 cmd_dtco = mkdir -p $(dir ${dtc-tmp}) ; \
-	$(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
+	$(file >$(dtc-flags-tmp),$(dtc_cpp_flags)) \
+	$(CPP) @$(dtc-flags-tmp) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
 	$(DTC) -@ -O dtb -o $@ -b 0 \
 		-i $(dir $<) $(DTC_FLAGS) \
 		-d $(depfile).dtc.tmp $(dtc-tmp) ; \
-- 
2.43.7

Re: [PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[Tom Rini]

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On Mon, Aug 24, 2026 at 10:17:18AM +0530, Suraj Kakade wrote:

> cmd_dtc inlines dtc_cpp_flags (including every upstream dtsi -I
> path) in the HOSTCC command. With a long $(srctree) that command is
> too large for /bin/sh -c and Make fails with "Argument list too
> long" while building a .dtb.
> 
> Write the flags to a per-target .dtc.flags.tmp file and pass @file to
> HOSTCC/CPP so the shell command stays short.
> 
> This change requires GNU Make >= 4.0, since $(file ...) is not
> supported by Make 3.x.
> 
> Fixes: d31ff219a833 ("Makefile.lib: find capsule ESL dtsi file with CONFIG_OF_UPSTREAM")
> Fixes: 1e7883f6325a ("dtbo: Fix dtbo generation rules")
> Signed-off-by: Suraj Kakade <suraj.hanumantkakade@amd.com>

The linux kernel, and so Kbuild, says that 4.0 is the minimum version of
GNU make required, so that is true for us as well, so this is fine.

Reviewed-by: Tom Rini <trini@konsulko.com>

-- 
Tom

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Re: [PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[Michal Simek]

On 8/24/26 17:09, Tom Rini wrote:
> On Mon, Aug 24, 2026 at 10:17:18AM +0530, Suraj Kakade wrote:
> 
>> cmd_dtc inlines dtc_cpp_flags (including every upstream dtsi -I
>> path) in the HOSTCC command. With a long $(srctree) that command is
>> too large for /bin/sh -c and Make fails with "Argument list too
>> long" while building a .dtb.
>>
>> Write the flags to a per-target .dtc.flags.tmp file and pass @file to
>> HOSTCC/CPP so the shell command stays short.
>>
>> This change requires GNU Make >= 4.0, since $(file ...) is not
>> supported by Make 3.x.
>>
>> Fixes: d31ff219a833 ("Makefile.lib: find capsule ESL dtsi file with CONFIG_OF_UPSTREAM")
>> Fixes: 1e7883f6325a ("dtbo: Fix dtbo generation rules")
>> Signed-off-by: Suraj Kakade <suraj.hanumantkakade@amd.com>
> 
> The linux kernel, and so Kbuild, says that 4.0 is the minimum version of
> GNU make required, so that is true for us as well, so this is fine.
> 
> Reviewed-by: Tom Rini <trini@konsulko.com>
> 

We should likely fix this too.

   94 # If the user is running make -s (silent mode), suppress echoing of
   95 # commands
   96 ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
   97 ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
   98   quiet=silent_
   99 endif
  100 else                                    # make-3.8x
  101 ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
  102   quiet=silent_
  103 endif
  104 endif

Thanks,
Michal

Re: [PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[Tom Rini]

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On Mon, Aug 24, 2026 at 05:29:37PM +0200, Michal Simek wrote:
> 
> 
> On 8/24/26 17:09, Tom Rini wrote:
> > On Mon, Aug 24, 2026 at 10:17:18AM +0530, Suraj Kakade wrote:
> > 
> > > cmd_dtc inlines dtc_cpp_flags (including every upstream dtsi -I
> > > path) in the HOSTCC command. With a long $(srctree) that command is
> > > too large for /bin/sh -c and Make fails with "Argument list too
> > > long" while building a .dtb.
> > > 
> > > Write the flags to a per-target .dtc.flags.tmp file and pass @file to
> > > HOSTCC/CPP so the shell command stays short.
> > > 
> > > This change requires GNU Make >= 4.0, since $(file ...) is not
> > > supported by Make 3.x.
> > > 
> > > Fixes: d31ff219a833 ("Makefile.lib: find capsule ESL dtsi file with CONFIG_OF_UPSTREAM")
> > > Fixes: 1e7883f6325a ("dtbo: Fix dtbo generation rules")
> > > Signed-off-by: Suraj Kakade <suraj.hanumantkakade@amd.com>
> > 
> > The linux kernel, and so Kbuild, says that 4.0 is the minimum version of
> > GNU make required, so that is true for us as well, so this is fine.
> > 
> > Reviewed-by: Tom Rini <trini@konsulko.com>
> > 
> 
> We should likely fix this too.
> 
>   94 # If the user is running make -s (silent mode), suppress echoing of
>   95 # commands
>   96 ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
>   97 ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
>   98   quiet=silent_
>   99 endif
>  100 else                                    # make-3.8x
>  101 ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
>  102   quiet=silent_
>  103 endif
>  104 endif

I think this means we should pull commit
5f99665ee8f4335f334a5292b6d5b41a577fc2c0 from the kernel in, to fully
switch to 4.0 as minimum.

-- 
Tom

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Re: [PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[Michal Simek]

On 8/24/26 18:51, Tom Rini wrote:
> On Mon, Aug 24, 2026 at 05:29:37PM +0200, Michal Simek wrote:
>>
>>
>> On 8/24/26 17:09, Tom Rini wrote:
>>> On Mon, Aug 24, 2026 at 10:17:18AM +0530, Suraj Kakade wrote:
>>>
>>>> cmd_dtc inlines dtc_cpp_flags (including every upstream dtsi -I
>>>> path) in the HOSTCC command. With a long $(srctree) that command is
>>>> too large for /bin/sh -c and Make fails with "Argument list too
>>>> long" while building a .dtb.
>>>>
>>>> Write the flags to a per-target .dtc.flags.tmp file and pass @file to
>>>> HOSTCC/CPP so the shell command stays short.
>>>>
>>>> This change requires GNU Make >= 4.0, since $(file ...) is not
>>>> supported by Make 3.x.
>>>>
>>>> Fixes: d31ff219a833 ("Makefile.lib: find capsule ESL dtsi file with CONFIG_OF_UPSTREAM")
>>>> Fixes: 1e7883f6325a ("dtbo: Fix dtbo generation rules")
>>>> Signed-off-by: Suraj Kakade <suraj.hanumantkakade@amd.com>
>>>
>>> The linux kernel, and so Kbuild, says that 4.0 is the minimum version of
>>> GNU make required, so that is true for us as well, so this is fine.
>>>
>>> Reviewed-by: Tom Rini <trini@konsulko.com>
>>>
>>
>> We should likely fix this too.
>>
>>    94 # If the user is running make -s (silent mode), suppress echoing of
>>    95 # commands
>>    96 ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
>>    97 ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
>>    98   quiet=silent_
>>    99 endif
>>   100 else                                    # make-3.8x
>>   101 ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
>>   102   quiet=silent_
>>   103 endif
>>   104 endif
> 
> I think this means we should pull commit
> 5f99665ee8f4335f334a5292b6d5b41a577fc2c0 from the kernel in, to fully
> switch to 4.0 as minimum.
> 

something like this?

M

diff --git a/Makefile b/Makefile
index 16e3e4dfe5e4..e0ab39200c1b 100644
--- a/Makefile
+++ b/Makefile
@@ -93,15 +93,9 @@ endif

  # If the user is running make -s (silent mode), suppress echoing of
  # commands
-ifneq ($(filter 4.%,$(MAKE_VERSION)),) # make-4
-ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
+ifneq ($(findstring s,$(firstword -$(MAKEFLAGS))),)
    quiet=silent_
  endif
-else                                   # make-3.8x
-ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
-  quiet=silent_
-endif
-endif

  export quiet Q KBUILD_VERBOSE

@@ -166,14 +160,6 @@ ifneq ($(abs_srctree),$(abs_objtree))
  MAKEFLAGS += --include-dir=$(abs_srctree)
  endif

-ifneq ($(filter 3.%,$(MAKE_VERSION)),)
-# 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
-# We need to invoke sub-make to avoid implicit rules in the top Makefile.
-need-sub-make := 1
-# Cancel implicit rules for this Makefile.
-$(this-makefile): ;
-endif
-
  export abs_srctree abs_objtree
  export sub_make_done := 1

Re: [PATCH RFC] scripts: pass dtc cpp flags via a GCC response file

[Tom Rini]

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On Tue, Aug 25, 2026 at 07:53:10AM +0200, Michal Simek wrote:
> 
> 
> On 8/24/26 18:51, Tom Rini wrote:
> > On Mon, Aug 24, 2026 at 05:29:37PM +0200, Michal Simek wrote:
> > > 
> > > 
> > > On 8/24/26 17:09, Tom Rini wrote:
> > > > On Mon, Aug 24, 2026 at 10:17:18AM +0530, Suraj Kakade wrote:
> > > > 
> > > > > cmd_dtc inlines dtc_cpp_flags (including every upstream dtsi -I
> > > > > path) in the HOSTCC command. With a long $(srctree) that command is
> > > > > too large for /bin/sh -c and Make fails with "Argument list too
> > > > > long" while building a .dtb.
> > > > > 
> > > > > Write the flags to a per-target .dtc.flags.tmp file and pass @file to
> > > > > HOSTCC/CPP so the shell command stays short.
> > > > > 
> > > > > This change requires GNU Make >= 4.0, since $(file ...) is not
> > > > > supported by Make 3.x.
> > > > > 
> > > > > Fixes: d31ff219a833 ("Makefile.lib: find capsule ESL dtsi file with CONFIG_OF_UPSTREAM")
> > > > > Fixes: 1e7883f6325a ("dtbo: Fix dtbo generation rules")
> > > > > Signed-off-by: Suraj Kakade <suraj.hanumantkakade@amd.com>
> > > > 
> > > > The linux kernel, and so Kbuild, says that 4.0 is the minimum version of
> > > > GNU make required, so that is true for us as well, so this is fine.
> > > > 
> > > > Reviewed-by: Tom Rini <trini@konsulko.com>
> > > > 
> > > 
> > > We should likely fix this too.
> > > 
> > >    94 # If the user is running make -s (silent mode), suppress echoing of
> > >    95 # commands
> > >    96 ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
> > >    97 ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
> > >    98   quiet=silent_
> > >    99 endif
> > >   100 else                                    # make-3.8x
> > >   101 ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
> > >   102   quiet=silent_
> > >   103 endif
> > >   104 endif
> > 
> > I think this means we should pull commit
> > 5f99665ee8f4335f334a5292b6d5b41a577fc2c0 from the kernel in, to fully
> > switch to 4.0 as minimum.
> > 
> 
> something like this?
> 
> M
> 
> diff --git a/Makefile b/Makefile
> index 16e3e4dfe5e4..e0ab39200c1b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -93,15 +93,9 @@ endif
> 
>  # If the user is running make -s (silent mode), suppress echoing of
>  # commands
> -ifneq ($(filter 4.%,$(MAKE_VERSION)),) # make-4
> -ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
> +ifneq ($(findstring s,$(firstword -$(MAKEFLAGS))),)
>    quiet=silent_
>  endif
> -else                                   # make-3.8x
> -ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
> -  quiet=silent_
> -endif
> -endif
> 
>  export quiet Q KBUILD_VERBOSE
> 
> @@ -166,14 +160,6 @@ ifneq ($(abs_srctree),$(abs_objtree))
>  MAKEFLAGS += --include-dir=$(abs_srctree)
>  endif
> 
> -ifneq ($(filter 3.%,$(MAKE_VERSION)),)
> -# 'MAKEFLAGS += -rR' does not immediately become effective for GNU Make 3.x
> -# We need to invoke sub-make to avoid implicit rules in the top Makefile.
> -need-sub-make := 1
> -# Cancel implicit rules for this Makefile.
> -$(this-makefile): ;
> -endif
> -
>  export abs_srctree abs_objtree
>  export sub_make_done := 1

And also the version check part (which we didn't add the initial part of
yet either, which checks for 3.8). Thanks!

-- 
Tom

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