1) Issue

When site-config-xxxx script (tobe included in SDK and referred by CONFIG_SITE in SDK environment) is generated, it is appended
by HOST arch/os information instead of the TARGET arch/os information.

2) Symptom

Yocto ver: jethro
Host: x86_64
Target: arm (32bit)

Build SDK, setting SDKMACHINE to x86_64.

After SDK is generated, install it and source its environment-setup script.

And if I invoke $CC (arm-poky-linux-gnueabi-gcc), using this SDK, sizeof (long) is 4 (long = int)

However, if I look into $CONFIG_SITE's definition of ac_cv_sizeof_long, it is defined as '8'.
I feel this is strange since if this cached configure data is for the target (and cross-compiling), this value should be 4, to match the above (arm-poky-linux-gnueabi-gcc) result.
(I think this part of the cache is being copied from poky/meta/site/x86_64-linux, )

This is causing break if I build autotool based program using the SDK.

3) Analysis

If I look into toolchain-scripts.bbclass, I can see toolchain_create_sdk_siteconfig is gathering site-config information from the following two lists:

1) TOOLCHAIN_CONFIGSITE_NOCACHE
2) TOOLCHAIN_NEED_CONFIGSITE_CACHE

2) Seems to be OK, since it is getting the sitefiles from the target files.
However, 1) is gathering the sitefiles by calling siteinfo_get_files().
If I look into siteinfo_get_files(), it returns information on HOST_ARCH-HOST_OS pair (here, I think HOST_ARCH-HOST_OS is not that of my target machine but my x86_64 HOST)

In fact, if I debug bitbake behavior, I can see following files are actually appended as TOOLCHAIN_CONFIGSITE_NOCACHE files.

xxx/meta-oe/site/endian-little
xxx/poky/meta/site/endian-little
xxx/poky/meta/site/ix86_common
xxx/poky/meta/site/common-linux
xxx/poky/meta/site/common-glibc
xxx/poky/meta/site/common

I think for toolchain_create_sdk_siteconfig(), TARGET_ARCH-TARGET_OS pair should be used to generate this list. 

(toolchain-scripts.bbclass excerpt)

#we get the cached site config in the runtime
TOOLCHAIN_CONFIGSITE_NOCACHE = "${@siteinfo_get_files(d, True)}"
TOOLCHAIN_CONFIGSITE_SYSROOTCACHE = "${STAGING_DIR}/${MLPREFIX}${MACHINE}/${target_datadir}/${TARGET_SYS}_config_site.d"
TOOLCHAIN_NEED_CONFIGSITE_CACHE ??= "virtual/${MLPREFIX}libc ncurses"

#This function create a site config file
toolchain_create_sdk_siteconfig () {
	local siteconfig=$1

	rm -f $siteconfig
	touch $siteconfig

	for sitefile in ${TOOLCHAIN_CONFIGSITE_NOCACHE} ; do
		cat $sitefile >> $siteconfig
	done

	#get cached site config
	for sitefile in ${TOOLCHAIN_NEED_CONFIGSITE_CACHE}; do
		# Resolve virtual/* names to the real recipe name using sysroot-providers info
		case $sitefile in virtual/*)
			sitefile=`echo $sitefile | tr / _`
			sitefile=`cat ${STAGING_DIR_TARGET}/sysroot-providers/$sitefile`
		esac

		if [ -r ${TOOLCHAIN_CONFIGSITE_SYSROOTCACHE}/${sitefile}_config ]; then
			cat ${TOOLCHAIN_CONFIGSITE_SYSROOTCACHE}/${sitefile}_config >> $siteconfig
		fi
	done
}