[PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David VomLehn]

Most platforms can get by perfectly well with the default command line size,
but some platforms need more. This patch allows the command line size to
be configured for those platforms that need it. The default remains 256
characters.

Signed-off-by: David VomLehn <dvomlehn@cisco.com>
---
 arch/mips/Kconfig             |    7 +++++++
 arch/mips/include/asm/setup.h |    2 +-
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 998e5db..99f7b6d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -780,6 +780,13 @@ config EARLY_PRINTK
 config SYS_HAS_EARLY_PRINTK
 	bool
 
+config COMMAND_LINE_SIZE
+	int "Maximum size of command line passed to kernel from bootloader"
+	default 256
+	help
+	  Most systems work well with the default value, but some bootloaders pass more
+	  information on the command line than others. A smaller value is good here.
+
 config HOTPLUG_CPU
 	bool
 	default n
diff --git a/arch/mips/include/asm/setup.h b/arch/mips/include/asm/setup.h
index e600ced..132e397 100644
--- a/arch/mips/include/asm/setup.h
+++ b/arch/mips/include/asm/setup.h
@@ -1,7 +1,7 @@
 #ifndef _MIPS_SETUP_H
 #define _MIPS_SETUP_H
 
-#define COMMAND_LINE_SIZE	256
+#define COMMAND_LINE_SIZE	CONFIG_COMMAND_LINE_SIZE
 
 #ifdef  __KERNEL__
 extern void setup_early_printk(void);

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Ralf Baechle]

On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:

> Most platforms can get by perfectly well with the default command line size,
> but some platforms need more. This patch allows the command line size to
> be configured for those platforms that need it. The default remains 256
> characters.
> 
> Signed-off-by: David VomLehn <dvomlehn@cisco.com>

How big of a command line do you need?  For no scientific reason other
than there not being any obvious need for a larger size MIPS is using 256
and I think unless you're asking for a huge number it will be better to
just raise that constant.

  Ralf

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Jon Fraser]

David,

We found huge command lines to be awkward.  In our platform support
code, we can pass environment variables from our bootstrap (CFE) to the
kernel.  Would something like this work for you?

I have no objection to making the command line buffer size bigger.

Jon



On Wed, 2009-05-06 at 09:35 -0700, Ralf Baechle wrote:
> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
> 
> > Most platforms can get by perfectly well with the default command line size,
> > but some platforms need more. This patch allows the command line size to
> > be configured for those platforms that need it. The default remains 256
> > characters.
> > 
> > Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> 
> How big of a command line do you need?  For no scientific reason other
> than there not being any obvious need for a larger size MIPS is using 256
> and I think unless you're asking for a huge number it will be better to
> just raise that constant.
> 
>   Ralf
> 
> 

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Jon Fraser]

David,

We found huge command lines to be awkward.  In our platform support
code, we can pass environment variables from our bootstrap (CFE) to the
kernel.  Would something like this work for you?

I have no objection to making the command line buffer size bigger.

Jon



On Wed, 2009-05-06 at 09:35 -0700, Ralf Baechle wrote:
> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
> 
> > Most platforms can get by perfectly well with the default command line size,
> > but some platforms need more. This patch allows the command line size to
> > be configured for those platforms that need it. The default remains 256
> > characters.
> > 
> > Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> 
> How big of a command line do you need?  For no scientific reason other
> than there not being any obvious need for a larger size MIPS is using 256
> and I think unless you're asking for a huge number it will be better to
> just raise that constant.
> 
>   Ralf
> 
> 

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David VomLehn]

On Wed, May 06, 2009 at 12:44:00PM -0400, Jon Fraser wrote:
> David,
> 
> We found huge command lines to be awkward.  In our platform support
> code, we can pass environment variables from our bootstrap (CFE) to the
> kernel.  Would something like this work for you?

I agree that large command lines are awkward. Environment variables are
the standard Linux way to pass the bulk of what we pass on the command line.
Unfortunately, the kernel team does not own the bootloader and consideration
for making the bootloader/kernel interface look like other platforms does
not appear to have a high priority. So, I'm stuck with using the command
line for everything.

> Jon

David

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Manuel Lauss]

On Wed, May 06, 2009 at 05:35:18PM +0100, Ralf Baechle wrote:
> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
> 
> > Most platforms can get by perfectly well with the default command line size,
> > but some platforms need more. This patch allows the command line size to
> > be configured for those platforms that need it. The default remains 256
> > characters.
> > 
> > Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> 
> How big of a command line do you need?  For no scientific reason other
> than there not being any obvious need for a larger size MIPS is using 256
> and I think unless you're asking for a huge number it will be better to
> just raise that constant.

FWIW, I like this change.  For my uses, 512 has been enough for >2 years
now.

	Manuel Lauss

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David VomLehn]

On Wed, May 06, 2009 at 05:35:18PM +0100, Ralf Baechle wrote:
> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
> 
> > Most platforms can get by perfectly well with the default command line size,
> > but some platforms need more. This patch allows the command line size to
> > be configured for those platforms that need it. The default remains 256
> > characters.
> > 
> > Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> 
> How big of a command line do you need?  For no scientific reason other
> than there not being any obvious need for a larger size MIPS is using 256
> and I think unless you're asking for a huge number it will be better to
> just raise that constant.

The answer depends on the platform, but it's at 438 characters on a typical
platform. If I *had* to pick a number, I'd probably go for 512 characters; I
just hate to force others to use memory they aren't going to use.

>   Ralf

David

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David Daney]

David VomLehn wrote:
> On Wed, May 06, 2009 at 05:35:18PM +0100, Ralf Baechle wrote:
>> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
>>
>>> Most platforms can get by perfectly well with the default command line size,
>>> but some platforms need more. This patch allows the command line size to
>>> be configured for those platforms that need it. The default remains 256
>>> characters.
>>>
>>> Signed-off-by: David VomLehn <dvomlehn@cisco.com>
>> How big of a command line do you need?  For no scientific reason other
>> than there not being any obvious need for a larger size MIPS is using 256
>> and I think unless you're asking for a huge number it will be better to
>> just raise that constant.
> 
> The answer depends on the platform, but it's at 438 characters on a typical
> platform. If I *had* to pick a number, I'd probably go for 512 characters; I
> just hate to force others to use memory they aren't going to use.
> 

I wonder if the memory could be dynamically allocated.  It would of 
course be a much larger patch.

David Daney

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Jon Fraser]

On Wed, 2009-05-06 at 11:24 -0700, David Daney wrote:
> David VomLehn wrote:
> > On Wed, May 06, 2009 at 05:35:18PM +0100, Ralf Baechle wrote:
> >> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
> >>
> >>> Most platforms can get by perfectly well with the default command line size,
> >>> but some platforms need more. This patch allows the command line size to
> >>> be configured for those platforms that need it. The default remains 256
> >>> characters.
> >>>
> >>> Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> >> How big of a command line do you need?  For no scientific reason other
> >> than there not being any obvious need for a larger size MIPS is using 256
> >> and I think unless you're asking for a huge number it will be better to
> >> just raise that constant.
> > 
> > The answer depends on the platform, but it's at 438 characters on a typical
> > platform. If I *had* to pick a number, I'd probably go for 512 characters; I
> > just hate to force others to use memory they aren't going to use.
> > 
> 
> I wonder if the memory could be dynamically allocated.  It would of 
> course be a much larger patch.
> 
> David Daney
> 



A bit of a chicken and egg problem if your command line arguments
set the memory configuration.


Jon Fraser
Broadcom

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David Daney]

Jon Fraser wrote:
> 
> On Wed, 2009-05-06 at 11:24 -0700, David Daney wrote:
>> David VomLehn wrote:
>>> On Wed, May 06, 2009 at 05:35:18PM +0100, Ralf Baechle wrote:
>>>> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
>>>>
>>>>> Most platforms can get by perfectly well with the default command line size,
>>>>> but some platforms need more. This patch allows the command line size to
>>>>> be configured for those platforms that need it. The default remains 256
>>>>> characters.
>>>>>
>>>>> Signed-off-by: David VomLehn <dvomlehn@cisco.com>
>>>> How big of a command line do you need?  For no scientific reason other
>>>> than there not being any obvious need for a larger size MIPS is using 256
>>>> and I think unless you're asking for a huge number it will be better to
>>>> just raise that constant.
>>> The answer depends on the platform, but it's at 438 characters on a typical
>>> platform. If I *had* to pick a number, I'd probably go for 512 characters; I
>>> just hate to force others to use memory they aren't going to use.
>>>
>> I wonder if the memory could be dynamically allocated.  It would of 
>> course be a much larger patch.
>>
>> David Daney
>>
> 
> 
> 
> A bit of a chicken and egg problem if your command line arguments
> set the memory configuration.
> 

I was thinking of putting it in __initdata memory, and then copying it 
to dynamically allocated memory before freeing the init memory.

David Daney

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David VomLehn]

On Wed, May 06, 2009 at 02:27:36PM -0400, Jon Fraser wrote:
> 
> 
> On Wed, 2009-05-06 at 11:24 -0700, David Daney wrote:
> > David VomLehn wrote:
> > > On Wed, May 06, 2009 at 05:35:18PM +0100, Ralf Baechle wrote:
> > >> On Mon, May 04, 2009 at 03:57:19PM -0700, David VomLehn wrote:
> > >>
> > >>> Most platforms can get by perfectly well with the default command line size,
> > >>> but some platforms need more. This patch allows the command line size to
> > >>> be configured for those platforms that need it. The default remains 256
> > >>> characters.
> > >>>
> > >>> Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> > >> How big of a command line do you need?  For no scientific reason other
> > >> than there not being any obvious need for a larger size MIPS is using 256
> > >> and I think unless you're asking for a huge number it will be better to
> > >> just raise that constant.
> > > 
> > > The answer depends on the platform, but it's at 438 characters on a typical
> > > platform. If I *had* to pick a number, I'd probably go for 512 characters; I
> > > just hate to force others to use memory they aren't going to use.
> > > 
> > 
> > I wonder if the memory could be dynamically allocated.  It would of 
> > course be a much larger patch.
> > 
> > David Daney
> 
> A bit of a chicken and egg problem if your command line arguments
> set the memory configuration.
> 
> Jon Fraser

You could wait for a final copy of the command line until *after* you have at
least the boot memory allocator working. Then other buffers used to hold
the command line would be __initdata.  Sounds like a bit of work, though, and
it might be kind of fragile for such a small gain in memory.

David VomLehn

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Paul Gortmaker]

On Mon, May 4, 2009 at 6:57 PM, David VomLehn <dvomlehn@cisco.com> wrote:
> Most platforms can get by perfectly well with the default command line size,
> but some platforms need more. This patch allows the command line size to
> be configured for those platforms that need it. The default remains 256
> characters.

The one thing I see when I look at this patch, is that it lands in the
arch/mips/Kconfig -- but is there really anything fundamentally
architecture specific about the allowed length of the kernel command
line?.  It probably belongs somewhere alongside the setting for
LOG_BUF_LEN or similar (and then add the other respective changes
to make all arch actually respect the setting.)

Paul.

>
> Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> ---
>  arch/mips/Kconfig             |    7 +++++++
>  arch/mips/include/asm/setup.h |    2 +-
>  2 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 998e5db..99f7b6d 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -780,6 +780,13 @@ config EARLY_PRINTK
>  config SYS_HAS_EARLY_PRINTK
>        bool
>
> +config COMMAND_LINE_SIZE
> +       int "Maximum size of command line passed to kernel from bootloader"
> +       default 256
> +       help
> +         Most systems work well with the default value, but some bootloaders pass more
> +         information on the command line than others. A smaller value is good here.
> +
>  config HOTPLUG_CPU
>        bool
>        default n
> diff --git a/arch/mips/include/asm/setup.h b/arch/mips/include/asm/setup.h
> index e600ced..132e397 100644
> --- a/arch/mips/include/asm/setup.h
> +++ b/arch/mips/include/asm/setup.h
> @@ -1,7 +1,7 @@
>  #ifndef _MIPS_SETUP_H
>  #define _MIPS_SETUP_H
>
> -#define COMMAND_LINE_SIZE      256
> +#define COMMAND_LINE_SIZE      CONFIG_COMMAND_LINE_SIZE
>
>  #ifdef  __KERNEL__
>  extern void setup_early_printk(void);
>
>

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Paul Gortmaker]

On Mon, May 4, 2009 at 6:57 PM, David VomLehn <dvomlehn@cisco.com> wrote:
> Most platforms can get by perfectly well with the default command line size,
> but some platforms need more. This patch allows the command line size to
> be configured for those platforms that need it. The default remains 256
> characters.

The one thing I see when I look at this patch, is that it lands in the
arch/mips/Kconfig -- but is there really anything fundamentally
architecture specific about the allowed length of the kernel command
line?.  It probably belongs somewhere alongside the setting for
LOG_BUF_LEN or similar (and then add the other respective changes
to make all arch actually respect the setting.)

Paul.

>
> Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> ---
>  arch/mips/Kconfig             |    7 +++++++
>  arch/mips/include/asm/setup.h |    2 +-
>  2 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 998e5db..99f7b6d 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -780,6 +780,13 @@ config EARLY_PRINTK
>  config SYS_HAS_EARLY_PRINTK
>        bool
>
> +config COMMAND_LINE_SIZE
> +       int "Maximum size of command line passed to kernel from bootloader"
> +       default 256
> +       help
> +         Most systems work well with the default value, but some bootloaders pass more
> +         information on the command line than others. A smaller value is good here.
> +
>  config HOTPLUG_CPU
>        bool
>        default n
> diff --git a/arch/mips/include/asm/setup.h b/arch/mips/include/asm/setup.h
> index e600ced..132e397 100644
> --- a/arch/mips/include/asm/setup.h
> +++ b/arch/mips/include/asm/setup.h
> @@ -1,7 +1,7 @@
>  #ifndef _MIPS_SETUP_H
>  #define _MIPS_SETUP_H
>
> -#define COMMAND_LINE_SIZE      256
> +#define COMMAND_LINE_SIZE      CONFIG_COMMAND_LINE_SIZE
>
>  #ifdef  __KERNEL__
>  extern void setup_early_printk(void);
>
>

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David VomLehn]

On Fri, May 08, 2009 at 11:25:35AM -0400, Paul Gortmaker wrote:
> On Mon, May 4, 2009 at 6:57 PM, David VomLehn <dvomlehn@cisco.com> wrote:
> > Most platforms can get by perfectly well with the default command line size,
> > but some platforms need more. This patch allows the command line size to
> > be configured for those platforms that need it. The default remains 256
> > characters.
> 
> The one thing I see when I look at this patch, is that it lands in the
> arch/mips/Kconfig -- but is there really anything fundamentally
> architecture specific about the allowed length of the kernel command
> line?.  It probably belongs somewhere alongside the setting for
> LOG_BUF_LEN or similar (and then add the other respective changes
> to make all arch actually respect the setting.)
> 
> Paul.
> 
> >
> > Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> > ---
> >  arch/mips/Kconfig             |    7 +++++++
> >  arch/mips/include/asm/setup.h |    2 +-

The reason I put this configuration configuration in the architecture-
specific Kconfig is because COMMAND_LINE_SIZE is defined in the
architecture-specific file arch/mips/include/asm/setup.h. I strongly
agree that this really should not be an architecture-specific definition,
but it's much more complex to get a patch to change COMMAND_LINE_SIZE
in every architecture. Fixing in the MIPS tree seems like a good
start.

David VomLehn

Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[Paul Gortmaker]

[Re: [PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)] On 08/05/2009 (Fri 09:34) David VomLehn wrote:

> On Fri, May 08, 2009 at 11:25:35AM -0400, Paul Gortmaker wrote:
> > On Mon, May 4, 2009 at 6:57 PM, David VomLehn <dvomlehn@cisco.com> wrote:
> > > Most platforms can get by perfectly well with the default command line size,
> > > but some platforms need more. This patch allows the command line size to
> > > be configured for those platforms that need it. The default remains 256
> > > characters.
> > 
> > The one thing I see when I look at this patch, is that it lands in the
> > arch/mips/Kconfig -- but is there really anything fundamentally
> > architecture specific about the allowed length of the kernel command
> > line?.  It probably belongs somewhere alongside the setting for
> > LOG_BUF_LEN or similar (and then add the other respective changes
> > to make all arch actually respect the setting.)
> > 
> > Paul.
> > 
> > >
> > > Signed-off-by: David VomLehn <dvomlehn@cisco.com>
> > > ---
> > >  arch/mips/Kconfig             |    7 +++++++
> > >  arch/mips/include/asm/setup.h |    2 +-
> 
> The reason I put this configuration configuration in the architecture-
> specific Kconfig is because COMMAND_LINE_SIZE is defined in the
> architecture-specific file arch/mips/include/asm/setup.h. I strongly
> agree that this really should not be an architecture-specific definition,
> but it's much more complex to get a patch to change COMMAND_LINE_SIZE
> in every architecture. Fixing in the MIPS tree seems like a good
> start.

It shouldn't be much more complex, at least from a purely technical
point of view (i.e assuming no arch maintainers have a problem with it).
Now, if we tried to get all arch to agree on the same default value,
then I agree that might be more complex/interesting.

All the arch use pretty much the same boilerplate, so something like
this untested patch should work.  I thought about hiding it behind
CONFIG_EMBEDDED, but in theory a person could have some big server
blade with a long command line argument too....

Paul.
---------

[PATCH 2/3] mips:powertv: Make kernel command line size configurable (resend)

[David VomLehn]

Most platforms can get by perfectly well with the default command line size,
but some platforms need more. This patch allows the command line size to
be configured for those platforms that need it. The default remains 256
characters.

Signed-off-by: David VomLehn <dvomlehn@cisco.com>
---
 arch/mips/Kconfig             |    7 +++++++
 arch/mips/include/asm/setup.h |    2 +-
 2 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 998e5db..99f7b6d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -780,6 +780,13 @@ config EARLY_PRINTK
 config SYS_HAS_EARLY_PRINTK
 	bool
 
+config COMMAND_LINE_SIZE
+	int "Maximum size of command line passed to kernel from bootloader"
+	default 256
+	help
+	  Most systems work well with the default value, but some bootloaders pass more
+	  information on the command line than others. A smaller value is good here.
+
 config HOTPLUG_CPU
 	bool
 	default n
diff --git a/arch/mips/include/asm/setup.h b/arch/mips/include/asm/setup.h
index e600ced..132e397 100644
--- a/arch/mips/include/asm/setup.h
+++ b/arch/mips/include/asm/setup.h
@@ -1,7 +1,7 @@
 #ifndef _MIPS_SETUP_H
 #define _MIPS_SETUP_H
 
-#define COMMAND_LINE_SIZE	256
+#define COMMAND_LINE_SIZE	CONFIG_COMMAND_LINE_SIZE
 
 #ifdef  __KERNEL__
 extern void setup_early_printk(void);