mirror of https://github.com/Wind4/vlmcsd
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
111 lines
4.2 KiB
Plaintext
111 lines
4.2 KiB
Plaintext
9 years ago
|
Compilation and pre-built binaries FAQ
|
||
|
======================================
|
||
|
|
||
|
What is the best pre-built binary for my system or device?
|
||
|
----------------------------------------------------------
|
||
|
|
||
|
None. The best binary is compiled by yourself using a toolchain that is
|
||
|
optimized for your system or device in every respect.
|
||
|
|
||
|
|
||
|
How do I compile my own binary?
|
||
|
-------------------------------
|
||
|
|
||
|
On a full blown desktop system this is relativly easy. If not already done so,
|
||
|
install a C compiler (e.g. gcc or clang) through your packet manager, e.g.
|
||
|
"sudo apt-get install gcc" (Debian/Ubuntu) or "sudo yum install gcc"
|
||
|
(RedHat/Fedora).
|
||
|
|
||
|
Then cd to your vlmcsd directory and type "make". vlmcs and vlmcsd will
|
||
|
be built right away for your local system.
|
||
|
|
||
|
If you installed gcc and it is not the default compiler for your OS or
|
||
|
distribution, you may need to type "make CC=gcc" to explicitly select a
|
||
|
specific C compiller.
|
||
|
|
||
|
|
||
|
How do I compile a binary for my embedded device?
|
||
|
-------------------------------------------------
|
||
|
|
||
|
What you need is cross-compiling toolchain for your device. It consists of a
|
||
|
C compiler, libraries, header files and some tools (called binutils). The
|
||
|
toolchain must match the device in processor architecture, endianess, ABI,
|
||
|
library and header files version, library configuration, ...
|
||
|
|
||
|
If the endianess or ABI differs or the version of some library between
|
||
|
toolchain and device differs too much, the resulting binary does not run
|
||
|
on your device.
|
||
|
|
||
|
Once you have a proper toolchain (probably found on the Internet for download),
|
||
|
unpack it to any directory and type
|
||
|
|
||
|
"make CC=/path/to/toolchain/bindir/c-compiler-binary"
|
||
|
|
||
|
Building vlmcsd for using a cross-compiling toolchain is as easy as building
|
||
|
vlmcsd for your local machine. The only question is, whether this you have
|
||
|
a toolchain that actually matches your device.
|
||
|
|
||
|
Whenever you change any parameter of the make command line, you must "clean"
|
||
|
the source directory from intermediate files and output from previous runs
|
||
|
of make. You can do so by typeing "make clean" or force make to behave as if
|
||
|
the directory were clean by adding -B to the command line, e.g.
|
||
|
|
||
|
"make -B CC=/path/to/toolchain/bindir/c-compiler-binary"
|
||
|
|
||
|
|
||
|
I have downloaded several promising toolchains for my device but they all
|
||
|
don't work. Can I create my own toolchain?
|
||
|
-------------------------------------------------------------------------
|
||
|
|
||
|
You can use tools like buildroot or OpenWRT. Both are able to create toolchains
|
||
|
for many embedded devices. But this is out of the scope of this document.
|
||
|
If you are unable to walk through thousands of configuration options and make
|
||
|
the right choice, you may probably want to try the pre-built binaries.
|
||
|
|
||
|
|
||
|
How to choose a pre-built binary?
|
||
|
---------------------------------
|
||
|
|
||
|
The directory structure for the binaries is
|
||
|
|
||
|
binaries
|
||
|
+
|
||
|
+--<operating system>
|
||
|
+
|
||
|
+--<cpu arch>
|
||
|
+
|
||
|
+--<endianess> (omitted if CPU or OS does not allow multi-endianess)
|
||
|
+
|
||
|
+--<C-library>
|
||
|
|
||
|
<C-library> can also be "static". That means no special library is required.
|
||
|
Static binaries are much bigger and need more RAM than dynamic binaries but
|
||
|
are more likely to run on your system. Use a static binary only, if none of
|
||
|
the dynmic binaries run.
|
||
|
|
||
|
Don't get confused when a binary is named after an OS or a specific device,
|
||
|
e.g. the name contains "openwrt", "tomato" or "Fritzbox". This does not mean
|
||
|
that the binary will run only on that OS or on that device. It is a hint only
|
||
|
where I got or built the toolchain from.
|
||
|
|
||
|
|
||
|
How to determine the endianess of my system?
|
||
|
--------------------------------------------
|
||
|
|
||
|
- All Intel CPUs (x86, x32, x64) are little-endian only
|
||
|
- Windows is little-endian only even if the CPU support big-endian
|
||
|
- big-endian ARM is extremely uncommon. You can safely assume little-endian
|
||
|
- little-endian PowerPC virtually does not exist since only newer POWER7
|
||
|
and POWER8 CPUs support it. Always assume big-endian.
|
||
|
- For MIPS both little-endian and big-endian are common. Most Broadcomm and
|
||
|
TI chips run little-endian. Most Atheros and Ikanos CPUs run big-endian.
|
||
|
|
||
|
Try typing
|
||
|
echo -n I | od -o | awk 'FNR==1{ print substr($2,6,1)}'
|
||
|
|
||
|
This returns 1 for little-endian systems and 0 for big-endian systems. However
|
||
|
some devices do not have the od command and thus this method won't work.
|
||
|
|
||
|
|
||
|
|