Re: [microblaze-uclinux] doubt about uclinux distribution and toolchain concepts

[Philipp Hachtmann <hachti@xxxxxxxxx>]

Hi Moises,

> i know that you need mainly 3 "set" of files to build your own Petalinux 
> kernel: 1) the uClinux kernel (linux-2.6.x-petalogix directory), 2) the 
> uClinux distribution (petalinux-dist directory) and 3) the microblaze 
> gcc tool-chain (microblaze-uclinux-tools directory)
Hm, 1) and 2) come together as I remember... But you're right.


> but i am not sure what is the difference, or what is the function of 2) 
> and 3) ??, between uClinux distribution and the tool-chain??

1) is the Linux kernel source tree, containing all source files, header 
files, configuration files etc. needed to make a kernel.

2) The uCLinux distribution consists of the uCLinux kernel and a heap of 
sources of user space software and scripts which help you to get a root 
filesystem image that can be used with the uCLinux kernel. In fact, your 
kernel just boots and gets in panic, dying and crying, if you don't have 
a root filesystem containing software to be run on top of the kernel. At 
least one program is needed to have a working Linux system. Without a 
program, the kernel just has nothing to administrate and dies.
In the uCLinux dist you will find everything to make a small complete 
system, with init, login, a shell, reboot etc.
The PetaLinux consists of a customized Linux kernel tree and a 
customized ucLinux dist and some magic tools and scripts that help you 
to (nearly automagically) adapt your kernel and tools to your hardware 
design done with Xilinx EDK. There are also some ready to run reference 
designs in PetaLinux-dist.


> i know that uClinux distribution has tools to configure the kernel (like 
> menuconfig or xconfig), but what else?,
See above. menuconfig etc. are standard with bare uCLinux, too. But 
PetaLogix customized all the stuff. Or better: added some stuff.

> and the microblaze tool-chain 
> "include everything you need to build uclinux kernels under linux" (i 
> found this definition in a tutorial), then when i do - make dep all - 
> what tools are in action??
Ok, the toolchain. The most important part of the toolchain is the 
compiler, for microblaze it's a GNU gcc.
The other tools of the chain are the GNU assembler "as", the linker "ld" 
and some other utilities involved in creating runnable software from 
sources.
On a linux system, you will find gcc, as, ld etc. all installed. But 
they produce output for the platform your Linux is running on - most 
probably a PC. So if you want to compile code for another kind of CPU, 
you have to use a cross-compiler and cross-binutils (the compiler's 
little friends as mentioned above).
The compiler and his friends together form the toolchain. To distinguish 
them from your PC's native PC, their names are prefixed with either 
"mb-" (from Xilinx) or "microblaze-uclinux-" so that theyr names become 
mb-gcc, mb-as, mb-ld etc.


> when i buil my kernel or when i do my own 
> applications??
For BOTH, of course!

When compiling the kernel or userspace software, some script magic and 
tools contained in the sources are working hand in hand with the native 
toolchain (to compile the menuconfig stuff etc.) of your machine, GNU 
make, and, of course, the cross toolchain for your target processor.

> i am confused of what things do the uclinux distribution 
> and what things do the microblaze tool-chain.
I hope you find my superficial explanations helpful...

Best regards,

Philipp :-)



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