Thursday, March 13, 2014

[Cross-Compile] What's the difference of `./configure` option `--build`, `--host` and `--target`?

When using ./configure especially in cross-compiling purpose, I kind of confuse about the option --build and --host so that the following content is what I found on searching:

some remarks on specifying --host=<host>, --target=<target> and --build=<build
# kindly provided by Keith Marshall:
# 1) build
# this is *always* the platform on which you are running the build
# process; since we are building on Linux, this is unequivocally going to
# specify `linux', with the canonical form being `i686-pc-linux-gnu'.
#
# 2) host
# this is a tricky one: it specifies the platform on which whatever we
# are building is going to be run; for the cross-compiler itself, that's
# also `i686-pc-linux-gnu', but when we get to the stage of building the
# runtime support libraries to go with that cross-compiler, they must
# contain code which will run on the `i686-pc-mingw32' host, so the `host'
# specification should change to this, for the `runtime' and `w32api'
# stages of the build.
#
# 3) target
# this is probably the one which causes the most confusion; it is only
# relevant when building a cross-compiler, and it specifies where the code
# which is built by that cross-compiler itself will ultimately run; it
# should not need to be specified at all, for the `runtime' or `w32api',
# since these are already targetted to `i686-pc-mingw32' by a correct
# `host' specification.

And I found an answer after posting this question.. Still posting it here in case it helps someone else in the future.
http://jingfenghanmax.blogspot.in/2010/09/configure-with-host-target-and-build.html

As per this blog in my case
build will be i686-pc-linux-gnu ( My PC)
host will be mipsel-linux ( The platform I am going to run my code on)
target will be used if I am building a cross-compiling toolchain.
Since I am not building a toolchain, I didnt have to specify target.

 You will have to cross-compile libusb and then copy the library and
header files to a location where your toolchain can locate them. In
the case of CodeSourcery, you can put them in
cs_root/arm-none-linux-gnueabi/lib and
cs_root/arm-none-linux-gnueabi/include for example. You will also need
the library on the target's root filesystem unless you link it
statically, please mind the licencing implications if you do though.
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