+# Now, validate our (potentially fixed-up) OS.
+case $os in
+ # Sometimes we do "kernel-libc", so those need to count as OSes.
+ musl* | newlib* | relibc* | uclibc*)
+ ;;
+ # Likewise for "kernel-abi"
+ eabi* | gnueabi*)
+ ;;
+ # VxWorks passes extra cpu info in the 4th filed.
+ simlinux | simwindows | spe)
+ ;;
+ # Now accept the basic system types.
+ # The portable systems comes first.
+ # Each alternative MUST end in a * to match a version number.
+ gnu* | android* | bsd* | mach* | minix* | genix* | ultrix* | irix* \
+ | *vms* | esix* | aix* | cnk* | sunos | sunos[34]* \
+ | hpux* | unos* | osf* | luna* | dgux* | auroraux* | solaris* \
+ | sym* | plan9* | psp* | sim* | xray* | os68k* | v88r* \
+ | hiux* | abug | nacl* | netware* | windows* \
+ | os9* | macos* | osx* | ios* \
+ | mpw* | magic* | mmixware* | mon960* | lnews* \
+ | amigaos* | amigados* | msdos* | newsos* | unicos* | aof* \
+ | aos* | aros* | cloudabi* | sortix* | twizzler* \
+ | nindy* | vxsim* | vxworks* | ebmon* | hms* | mvs* \
+ | clix* | riscos* | uniplus* | iris* | isc* | rtu* | xenix* \
+ | mirbsd* | netbsd* | dicos* | openedition* | ose* \
+ | bitrig* | openbsd* | secbsd* | solidbsd* | libertybsd* | os108* \
+ | ekkobsd* | freebsd* | riscix* | lynxos* | os400* \
+ | bosx* | nextstep* | cxux* | aout* | elf* | oabi* \
+ | ptx* | coff* | ecoff* | winnt* | domain* | vsta* \
+ | udi* | lites* | ieee* | go32* | aux* | hcos* \
+ | chorusrdb* | cegcc* | glidix* | serenity* \
+ | cygwin* | msys* | pe* | moss* | proelf* | rtems* \
+ | midipix* | mingw32* | mingw64* | mint* \
+ | uxpv* | beos* | mpeix* | udk* | moxiebox* \
+ | interix* | uwin* | mks* | rhapsody* | darwin* \
+ | openstep* | oskit* | conix* | pw32* | nonstopux* \
+ | storm-chaos* | tops10* | tenex* | tops20* | its* \
+ | os2* | vos* | palmos* | uclinux* | nucleus* | morphos* \
+ | scout* | superux* | sysv* | rtmk* | tpf* | windiss* \
+ | powermax* | dnix* | nx6 | nx7 | sei* | dragonfly* \
+ | skyos* | haiku* | rdos* | toppers* | drops* | es* \
+ | onefs* | tirtos* | phoenix* | fuchsia* | redox* | bme* \
+ | midnightbsd* | amdhsa* | unleashed* | emscripten* | wasi* \
+ | nsk* | powerunix* | genode* | zvmoe* | qnx* | emx* | zephyr* \
+ | fiwix* )
+ ;;
+ # This one is extra strict with allowed versions
+ sco3.2v2 | sco3.2v[4-9]* | sco5v6*)
+ # Don't forget version if it is 3.2v4 or newer.
+ ;;
+ none)
+ ;;
+ *)
+ echo Invalid configuration \`"$1"\': OS \`"$os"\' not recognized 1>&2
+ exit 1
+ ;;
+esac
+
+# As a final step for OS-related things, validate the OS-kernel combination
+# (given a valid OS), if there is a kernel.
+case $kernel-$os in
+ linux-gnu* | linux-dietlibc* | linux-android* | linux-newlib* \
+ | linux-musl* | linux-relibc* | linux-uclibc* )
+ ;;
+ uclinux-uclibc* )
+ ;;
+ -dietlibc* | -newlib* | -musl* | -relibc* | -uclibc* )
+ # These are just libc implementations, not actual OSes, and thus
+ # require a kernel.
+ echo "Invalid configuration \`$1': libc \`$os' needs explicit kernel." 1>&2
+ exit 1
+ ;;
+ kfreebsd*-gnu* | kopensolaris*-gnu*)
+ ;;
+ vxworks-simlinux | vxworks-simwindows | vxworks-spe)
+ ;;
+ nto-qnx*)
+ ;;
+ os2-emx)
+ ;;
+ *-eabi* | *-gnueabi*)
+ ;;
+ -*)
+ # Blank kernel with real OS is always fine.
+ ;;
+ *-*)
+ echo "Invalid configuration \`$1': Kernel \`$kernel' not known to work with OS \`$os'." 1>&2
+ exit 1
+ ;;
+esac
+