[yocto] sysroot / external toolchain

[Dallas Clement]

I'm using an external toolchain for my project.  What is the proper
way to include my external toolchain libc files in the sysroot?

Currently I have

TOOLCHAIN_OPTIONS = " --sysroot=${STAGING_DIR_HOST}"

and

EXTERNAL_TOOLCHAIN_SYSROOT_CMD = "${TARGET_PREFIX}gcc
${TARGET_CC_ARCH} -print-sysroot"
EXTERNAL_TOOLCHAIN_SYSROOT ??= "${@exttc_run(d,
EXTERNAL_TOOLCHAIN_SYSROOT_CMD)}"

which resolves to
/opt/armada-sdk-5.0-64k/armv7-marvell-linux-gnueabi-softfp/arm-marvell-linux-gnueabi/libc/

I also have a recipe for my external toolchain which includes the following:

do_install() {
        # Use optimized files if available
        sysroot="${EXTERNAL_TOOLCHAIN_SYSROOT}"
}

The EXTERNAL_TOOLCHAIN_SYSROOT doesn't seem to have any effect.  My
libc header files are not visible during compilation. It looks like I
may have to copy them to the staging dir or setup some symlinks.  Is
this the right approach?

Thanks