linux: handle read-only dts files

Some fine version control systems make all files read-only. The custom DTS file may therefore be read-only, and that permission is preserved when copying into the Linux build directory. A subsequent rebuild tries to 'cp' again, which fails with a "Permission denied" error unless the -f option is used.

Signed-off-by Hollis Blanchard <[email protected]>

---
  linux/linux.mk | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

linux/linux.mk +0 -0

index 375a9e1..a4c4733 100644

Hi Holis,

Quoted 27 lines · Hollis Blanchard

Some fine version control systems make all files read-only. The custom DTS file
may therefore be read-only, and that permission is preserved when copying into
the Linux build directory. A subsequent rebuild tries to 'cp' again, which
fails with a "Permission denied" error unless the -f option is used.

Signed-off-by Hollis Blanchard <[email protected]>

---
  linux/linux.mk | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

linux/linux.mk +1 -1

index 375a9e1..a4c4733 100644
@@ -270,7 +270,7 @@ endif
  # configuration has changed.
  define LINUX_BUILD_CMDS
      $(if $(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),
-        cp $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)) 
 $(KERNEL_ARCH_PATH)/boot/dts/)
+        cp -f $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)) 
 $(KERNEL_ARCH_PATH)/boot/dts/)
      $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) 

$(LINUX_TARGET_NAME)

Quoted 4 lines

      @if grep -q "CONFIG_MODULES=y" $(@D)/.config; then     \
          $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) 

modules ; \

Is there a reason for the custom DTS to exist in both places?

Regards,
Nikolay

The DTS exists at $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) because that's where it lives. It's copied to $(KERNEL_ARCH_PATH)/boot/dts/ so that the kernel build process can build a DTB out of it (which is later copied to build/images/).

Or did I misunderstand the question?

Hollis Blanchard
Mentor Graphics Emulation Division

Quoted 39 lines · Nikolay Dimitrov

Hi Holis,

Quoted 27 lines · Hollis Blanchard

Some fine version control systems make all files read-only. The custom DTS file
may therefore be read-only, and that permission is preserved when copying into
the Linux build directory. A subsequent rebuild tries to 'cp' again, which
fails with a "Permission denied" error unless the -f option is used.

Signed-off-by Hollis Blanchard <[email protected]>

---
  linux/linux.mk | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

linux/linux.mk +1 -1

index 375a9e1..a4c4733 100644
@@ -270,7 +270,7 @@ endif
  # configuration has changed.
  define LINUX_BUILD_CMDS
      $(if $(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),
-        cp $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH))
 $(KERNEL_ARCH_PATH)/boot/dts/)
+        cp -f $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH))
 $(KERNEL_ARCH_PATH)/boot/dts/)
      $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D)

$(LINUX_TARGET_NAME)

Quoted 4 lines

      @if grep -q "CONFIG_MODULES=y" $(@D)/.config; then     \
          $(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D)

modules ; \

Is there a reason for the custom DTS to exist in both places?

Regards,
Nikolay

Hi Hollis,

Quoted 6 lines · Hollis Blanchard

The DTS exists at $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) because that's where it lives. It's copied to $(KERNEL_ARCH_PATH)/boot/dts/ so that the kernel build process can build a DTB out of it (which is later copied to build/images/).

Or did I misunderstand the question?

Sorry, I could've been probably more clear. My question was whether the DTS needs to exist also at the destination ($(KERNEL_ARCH_PATH)/boot /dts/) before the copying happens.

If it doesn't exist at the destination, the VCS wouldn't have checked it out as r/o file, and the issue wouldn't happen in the first place (e.g. the copy operation will succeed). Also, when we have 2 files with the same name and content, this tends to create confusion with developers (aka which file was the primary one).

Quoted 9 lines · Nikolay Dimitrov

Hi Hollis,

Quoted 6 lines · Hollis Blanchard

The DTS exists at $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) because that's where it lives. It's copied to $(KERNEL_ARCH_PATH)/boot/dts/ so that the kernel build process can build a DTB out of it (which is later copied to build/images/).

Or did I misunderstand the question?

(Just to be clear: $(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH) is under version control, while $(KERNEL_ARCH_PATH), the build directory, is not.)

Quoted 3 lines

Sorry, I could've been probably more clear. My question was whether the DTS needs to exist also at the destination ($(KERNEL_ARCH_PATH)/boot /dts/) before the copying happens.

It does not need to exist there. It's only there because of a previous cp in a previous build.

Quoted 6 lines

If it doesn't exist at the destination, the VCS wouldn't have checked it out as r/o file, and the issue wouldn't happen in the first place (e.g. the copy operation will succeed). Also, when we have 2 files with the same name and content, this tends to create confusion with developers (aka which file was the primary one).

The file needs to exist at the destination at least temporarily, for the DTS->DTB translation. You could say "we should remove it afterwards", but a) that could be technically difficult in the face of ^C and kill -9, and b) you could say the same about zImage, vmlinux, etc... so we'd really be talking about a full "make clean", which seems like overkill.

Are you suggesting "rm -f; cp" instead of "cp -f"? As far as I know the two are functionally equivalent, so the former seems like slightly more overhead to get the same effect as the latter.

cp -f seems a simple solution: try harder to copy the file. :-)

Hollis Blanchard
Mentor Graphics Emulation Division

Some fine version control systems make all files read-only. The custom DTS file may therefore be read-only, and that permission is preserved when copying into the Linux build directory. A subsequent rebuild tries to 'cp' again, which fails with a "Permission denied" error unless the -f option is used.

Signed-off-by Hollis Blanchard <[email protected]>

---
  linux/linux.mk | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

linux/linux.mk +0 -0

index 375a9e1..a4c4733 100644

Some fine version control systems make all files read-only. The custom DTS file may therefore be read-only, and that permission is preserved when copying into the Linux build directory. A subsequent rebuild tries to 'cp' again, which fails with a "Permission denied" error unless the -f option is used.

Signed-off-by Hollis Blanchard <[email protected]>

---
 linux/linux.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

linux/linux.mk +1 -1

index 375a9e1..a4c4733 100644
@@ -270,7 +270,7 @@ endif
 # configuration has changed.
 define LINUX_BUILD_CMDS
 	$(if $(BR2_LINUX_KERNEL_USE_CUSTOM_DTS),
-		cp $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)) $(KERNEL_ARCH_PATH)/boot/dts/)
+		cp -f $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)) $(KERNEL_ARCH_PATH)/boot/dts/)
 	$(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_TARGET_NAME)
 	@if grep -q "CONFIG_MODULES=y" $(@D)/.config; then 	\
 		$(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) modules ;	\

Signature · 6 lines

2.3.2

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Some fine version control systems make all files read-only. The custom DTS file may therefore be read-only, and that permission is preserved when copying into the Linux build directory. A subsequent rebuild tries to 'cp' again, which fails with a "Permission denied" error unless the -f option is used.

Signed-off-by Hollis Blanchard <[email protected]>

---
 linux/linux.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)