code: def all_arch_srcarch_pairs():
      
      for srcarch in os.listdir("arch"):
          # Each subdirectory of arch/ containing a Kconfig file corresponds to
          # an architecture
          if os.path.exists(os.path.join("arch", srcarch, "Kconfig")):
              yield (srcarch, srcarch)
  
      # Some architectures define additional ARCH settings with ARCH != SRCARCH
      # (search for "Additional ARCH settings for" in the top-level Makefile)
  
      yield ("i386", "x86")
      yield ("x86_64", "x86")
  
      yield ("sparc32", "sparc")
      yield ("sparc64", "sparc")
  
      yield ("sh64", "sh")
  
      yield ("um", "um")
docs: Generates all valid (ARCH, SRCARCH) tuples for the kernel, corresponding to
      different architectures. SRCARCH holds the arch/ subdirectory.