Is there a tool which can generate a small and simple source tree after config?

Is there a tool which can generate a small and simple source tree after config?

[jiangtao.jit]

Hi:

While reading the kernel code
1. the huge amount of files make me scared
    there are too many alike functions in different files
    sometimes I can't figure out which one was really compiled
2. too many macros in the definition of a struct or functions declaration
    confused me a lot
    I tried to follow the generated file autoconf.h to guess the final face
    but it's really a difficult thing

Is there a tool which can generate a small and simple source tree after config?
not pre-processor
just generate a small source tree contains the files and dirs which really will be compiled
and no macros like CONFIG_SMP etc.
according to the configuration

or some other way to understand the architecture of the final working source tree?

Thanks.

--
2011-10-23 
jiangtao.jit 

Is there a tool which can generate a small and simple source tree after config?

[Aiolia Lea]

hum, how about doxygen?

On Sun, Oct 23, 2011 at 6:29 PM, jiangtao.jit <jiangtao.jit@gmail.com>wrote:

> Hi:
>
> While reading the kernel code
> 1. the huge amount of files make me scared
>    there are too many alike functions in different files
>    sometimes I can't figure out which one was really compiled
> 2. too many macros in the definition of a struct or functions declaration
>    confused me a lot
>    I tried to follow the generated file autoconf.h to guess the final face
>    but it's really a difficult thing
>
> Is there a tool which can generate a small and simple source tree after
> config?
> not pre-processor
> just generate a small source tree contains the files and dirs which really
> will be compiled
> and no macros like CONFIG_SMP etc.
> according to the configuration
>
> or some other way to understand the architecture of the final working
> source tree?
>
> Thanks.
>
> --
> 2011-10-23
> jiangtao.jit
>
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>



-- 
Best Regards!
Aiolia Lea
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Is there a tool which can generate a small and simple source tree after config?

[Mulyadi Santosa]

Hi :)

On Sun, Oct 23, 2011 at 23:29, jiangtao.jit <jiangtao.jit@gmail.com> wrote:
> Is there a tool which can generate a small and simple source tree after config?
> not pre-processor
> just generate a small source tree contains the files and dirs which really will be compiled
> and no macros like CONFIG_SMP etc.
> according to the configuration
>
> or some other way to understand the architecture of the final working source tree?

I feel the same way too, even 'til now :)

The way I do it is maybe counter intuitive for you. I compile the
kernel image with frame pointer enabled and debug info (check kernel
hacking section in "make config" during kernel compilation).

Then, together with a disk image, I run this kernel in Qemu virtual
machine. While running, I hook gdb to this Qemu instance. Finally, I
put breakpoints, watchpoints, check backtraces etc I needed to
understand the flow.

Maybe that'll work for you too.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

Is there a tool which can generate a small and simple source tree after config?

[Javier Martinez Canillas]

On Sun, Oct 23, 2011 at 6:29 PM, jiangtao.jit <jiangtao.jit@gmail.com> wrote:
> Hi:
>

Hi jiangtao,

> While reading the kernel code
> 1. the huge amount of files make me scared
> ? ?there are too many alike functions in different files
> ? ?sometimes I can't figure out which one was really compiled
> 2. too many macros in the definition of a struct or functions declaration
> ? ?confused me a lot
> ? ?I tried to follow the generated file autoconf.h to guess the final face
> ? ?but it's really a difficult thing
>
> Is there a tool which can generate a small and simple source tree after config?
> not pre-processor

Not that I'm aware of.

> just generate a small source tree contains the files and dirs which really will be compiled
> and no macros like CONFIG_SMP etc.
> according to the configuration
>
> or some other way to understand the architecture of the final working source tree?
>

The Linux kernel is a very complex beast yet it is highly modularized.
I recommend you to focus on the specific subsystem that you need to
work and don't worry about the rest.

To know if a specific file is included in your kernel I usually do
this (it works for me but I'm not sure if is the right way to do it):

For example if I want to know if the driver to support nand memories
on ARM OMAP platforms is included in my kernel.

1- Find the file that implements the driver (drivers/mtd/nand/omap2.c)

2- See which Kconfig symbol determines its compilation:

$ fgrep omap2 drivers/mtd/nand/Makefile
obj-$(CONFIG_MTD_NAND_OMAP2) 		+= omap2.o

3- Look if that symbol is included in my config file:

$ fgrep MTD_NAND_OMAP2 .config
CONFIG_MTD_NAND_OMAP2=y

Then I know that my kernels includes that file.


Hope it helps,

-- 
Javier Mart?nez Canillas
(+34) 682 39 81 69
Barcelona, Spain