Porting%20Linux%20to%20the%20Puppeteer

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Porting Linux to the Puppeteer
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Getting the kernel source

• You will need a clean version of the linux kernel
  source
• This can be found at www.kernel.org or lots of
  mirror sites
• Probably best not to download the latest version
• Use the numbering system x.y.z
• Even is stable 2.4.9, 2.6.4 etc
• Odd is development 2.3.7, 2.5.9 etc

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Applying patches

• Linux is primarily used on Intel Pentium machines
• However other architectures are supported
• alpha, arm, i386, ia64, m86k, mips, mips64, ppc
  s390, sh, sparc, sparc64
• To support other architectures patches need
  applying to make specific changes to the source

4
Getting the ARM patches

• The ARM Linux patches can be found at
  www.arm.linux.org.uk
• You need to find the patch that applies to your
  particular kernel
• patch-2.4.18-rmk10.gz for 2.4.18
• There are specialised patches for specific
  features
• The patch must be applied to a clean source tree
  in the root of the kernel source
• Patch p1 patch-2.4.18-rmk10
• Beware of pre patches!

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The Linux kernel source

• In order to configure and port the kernel source
  you will need to know more about its structure.

/usr/src/linux
scripts
Documentation
init
ipc
kernel
mm
net
Include Asm-alpha Asm-arm Asm-generic Asm-i386
linux
FS adfs affs autofs ext2 fat
Drivers acorn atm block cdrom char i2c .
Arch alpha arm i386 ia64 m68k ..
lib
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The arch directories

• These contain specific code for each port
• It has
• Kernel, lib, mm, boot plus variants and board
  specifics
• Lib has optimised code for the hardware
• i.e. memcpy, checksums.

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Drivers directory

• Largest amount of code circa 1.5M
• The area you are most likely to have to
  port/maintain
• Details on buses
• Categories of device driver
• Char, block, net

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The include directory

• This is linked a configure time with architecture
  dependant subdirectories
• For example asm-arm
• Include/linux for kernel and user apps
• Beware for some start up code for example
  serial port code

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Linux/init

• This has 2 file version.c and main.c
• version.c has the version banner at boot time
• main.c is the architecture independent boot code
• start_kernel is the primary entry point