[PATCH] powerpc: Support CMDLINE_EXTEND

Device tree aware platforms can make use of CMDLINE_EXTEND to extend the
kernel command line provided by the bootloader. This is particularly
useful to set parameters for built-in modules that would otherwise be
done at module insertion. Add support for this in the powerpc
architecture.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
 arch/powerpc/Kconfig | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d8dcd8820369..cd9b3974aa36 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -851,6 +851,11 @@ config CMDLINE
 	  some command-line options at build time by entering them here.  In
 	  most cases you will need to specify the root device here.
 
+choice
+	prompt "Kernel command line type" if CMDLINE != ""
+	default CMDLINE_FORCE
+	depends on CMDLINE_BOOL
+
 config CMDLINE_FORCE
 	bool "Always use the default kernel command string"
 	depends on CMDLINE_BOOL

@@ -860,6 +865,13 @@ config CMDLINE_FORCE
 	  This is useful if you cannot or don't want to change the
 	  command-line options your boot loader passes to the kernel.
 
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The command-line arguments provided by the boot loader will be
+	  appended to the default kernel command string.
+endchoice
+
 config EXTRA_TARGETS
 	string "Additional default image types"
 	help

-- 
2.22.0

Le 24/07/2019 à 07:33, Chris Packham a écrit :

Device tree aware platforms can make use of CMDLINE_EXTEND to extend the
kernel command line provided by the bootloader. This is particularly
useful to set parameters for built-in modules that would otherwise be
done at module insertion. Add support for this in the powerpc
architecture.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
  arch/powerpc/Kconfig | 12 ++++++++++++

I think you also have to implement some stuff in early_cmdline_parse() in arch/powerpc/kernel/prom_init.c

Maybe look at https://patchwork.ozlabs.org/patch/1074126/

Christophe

Hi Christophe,

On Tue, 2019-07-30 at 09:02 +0200, Christophe Leroy wrote:

Le 24/07/2019 à 07:33, Chris Packham a écrit :

quoted

Device tree aware platforms can make use of CMDLINE_EXTEND to
extend the
kernel command line provided by the bootloader. This is
particularly
useful to set parameters for built-in modules that would otherwise
be
done at module insertion. Add support for this in the powerpc
architecture.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
  arch/powerpc/Kconfig | 12 ++++++++++++

I think you also have to implement some stuff in
early_cmdline_parse() 
in arch/powerpc/kernel/prom_init.c

I my case I didn't need to since the generic code in drivers/of/fdt.c
did what I need. For early options or platforms that don't use a device
tree then I can see why I'd need the update to update to prom_init.

Maybe look at https://patchwork.ozlabs.org/patch/1074126/

Do you mind if I take this and fold it into a v2 of my patch? Any
particular reason it didn't get picked up in April?

Christophe

quoted

  1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d8dcd8820369..cd9b3974aa36 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -851,6 +851,11 @@ config CMDLINE

  	  some command-line options at build time by entering
them here.  In
  	  most cases you will need to specify the root device
here.
  
+choice
+	prompt "Kernel command line type" if CMDLINE != ""
+	default CMDLINE_FORCE
+	depends on CMDLINE_BOOL
+
  config CMDLINE_FORCE
  	bool "Always use the default kernel command string"
  	depends on CMDLINE_BOOL

@@ -860,6 +865,13 @@ config CMDLINE_FORCE

  	  This is useful if you cannot or don't want to change
the
  	  command-line options your boot loader passes to the
kernel.
  
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The command-line arguments provided by the boot loader
will be
+	  appended to the default kernel command string.
+endchoice
+
  config EXTRA_TARGETS
  	string "Additional default image types"
  	help

Le 30/07/2019 à 23:10, Chris Packham a écrit :

Hi Christophe,

On Tue, 2019-07-30 at 09:02 +0200, Christophe Leroy wrote:

quoted

Le 24/07/2019 à 07:33, Chris Packham a écrit :

quoted

Device tree aware platforms can make use of CMDLINE_EXTEND to
extend the
kernel command line provided by the bootloader. This is
particularly
useful to set parameters for built-in modules that would otherwise
be
done at module insertion. Add support for this in the powerpc
architecture.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
   arch/powerpc/Kconfig | 12 ++++++++++++

I think you also have to implement some stuff in
early_cmdline_parse()
in arch/powerpc/kernel/prom_init.c

I my case I didn't need to since the generic code in drivers/of/fdt.c
did what I need. For early options or platforms that don't use a device
tree then I can see why I'd need the update to update to prom_init.

quoted

Maybe look at https://patchwork.ozlabs.org/patch/1074126/

Do you mind if I take this and fold it into a v2 of my patch? Any
particular reason it didn't get picked up in April?

Sure, take it, I don't mind.

Two reasons it was not picked up in April I believe:
- It was part of a larger series (https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=100518) and was intended to challenge the series proposed by Daniel (https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=98106) but nothing happened.
- It was conflicting with the ongoing changes for implementing KASAN.

What you will have to do is to define prom_strlcat() in the same spirit as https://patchwork.ozlabs.org/patch/1091621/ by copying it from lib/string.c and I think you'll be able to drop prom_strlcpy() as that function what only used there.

Christophe

quoted

Christophe

quoted

   1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d8dcd8820369..cd9b3974aa36 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -851,6 +851,11 @@ config CMDLINE
   	  some command-line options at build time by entering

them here.  In
   	  most cases you will need to specify the root device
here.
   
+choice
+	prompt "Kernel command line type" if CMDLINE != ""
+	default CMDLINE_FORCE
+	depends on CMDLINE_BOOL
+
   config CMDLINE_FORCE
   	bool "Always use the default kernel command string"
   	depends on CMDLINE_BOOL

@@ -860,6 +865,13 @@ config CMDLINE_FORCE
   	  This is useful if you cannot or don't want to change

the
   	  command-line options your boot loader passes to the
kernel.
   
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The command-line arguments provided by the boot loader
will be
+	  appended to the default kernel command string.
+endchoice
+
   config EXTRA_TARGETS
   	string "Additional default image types"
   	help

On Wed, 2019-07-31 at 09:23 +0200, Christophe Leroy wrote:

Le 30/07/2019 à 23:10, Chris Packham a écrit :

quoted

Hi Christophe,

On Tue, 2019-07-30 at 09:02 +0200, Christophe Leroy wrote:

quoted

Le 24/07/2019 à 07:33, Chris Packham a écrit :

quoted

Device tree aware platforms can make use of CMDLINE_EXTEND to
extend the
kernel command line provided by the bootloader. This is
particularly
useful to set parameters for built-in modules that would
otherwise
be
done at module insertion. Add support for this in the powerpc
architecture.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz

quoted

---
   arch/powerpc/Kconfig | 12 ++++++++++++

I think you also have to implement some stuff in
early_cmdline_parse()
in arch/powerpc/kernel/prom_init.c

I my case I didn't need to since the generic code
in drivers/of/fdt.c
did what I need. For early options or platforms that don't use a
device
tree then I can see why I'd need the update to update to prom_init.

quoted

Maybe look at https://patchwork.ozlabs.org/patch/1074126/

Do you mind if I take this and fold it into a v2 of my patch? Any
particular reason it didn't get picked up in April?

Sure, take it, I don't mind.

Two reasons it was not picked up in April I believe:
- It was part of a larger series 
(https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=10051
8) 
and was intended to challenge the series proposed by Daniel 
(https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=98106
) 
but nothing happened.
- It was conflicting with the ongoing changes for implementing KASAN.

What you will have to do is to define prom_strlcat() in the same
spirit 
as https://patchwork.ozlabs.org/patch/1091621/ by copying it from 
lib/string.c and 

Is it OK to use BUG_ON in prom_init? If I copy it verbatim then the
code from lib/string.c has a BUG_ON. I could probably change that to
if(x) return -1 if BUG_ON is not appropriate.

I think you'll be able to drop prom_strlcpy() as that 
function what only used there.

I think I need to keep prom_strlcpy to handle the CMDLINE_FORCE case.

Christophe

quoted

quoted

Christophe

quoted

   1 file changed, 12 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d8dcd8820369..cd9b3974aa36 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -851,6 +851,11 @@ config CMDLINE

   	  some command-line options at build time by
entering
them here.  In
   	  most cases you will need to specify the root
device
here.
   
+choice
+	prompt "Kernel command line type" if CMDLINE != ""
+	default CMDLINE_FORCE
+	depends on CMDLINE_BOOL
+
   config CMDLINE_FORCE
   	bool "Always use the default kernel command string"
   	depends on CMDLINE_BOOL

@@ -860,6 +865,13 @@ config CMDLINE_FORCE

   	  This is useful if you cannot or don't want to
change
the
   	  command-line options your boot loader passes to
the
kernel.
   
+config CMDLINE_EXTEND
+	bool "Extend bootloader kernel arguments"
+	help
+	  The command-line arguments provided by the boot
loader
will be
+	  appended to the default kernel command string.
+endchoice
+
   config EXTRA_TARGETS
   	string "Additional default image types"
   	help