x86: Support compiling out human-friendly processor feature names

The table mapping CPUID bits to human-readable strings takes up a
non-trivial amount of space, and only exists to support /proc/cpuinfo
and a couple of kernel messages.  Since programs depend on the format of
/proc/cpuinfo, force inclusion of the table when building with /proc
support; otherwise, support omitting that table to save space, in which
case the kernel messages will print features numerically instead.

In addition to saving 1408 bytes out of vmlinux, this also saves 1373
bytes out of the uncompressed setup code, which contributes directly to
the size of bzImage.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>

2 files changed, 46 insertions, 29 deletions

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index dbe8dd2fe247..5b016e2498f3 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -35,19 +35,22 @@ setup-y		+= video-vesa.o
 setup-y         += video-bios.o
 
 targets         += $(setup-y)
-hostprogs-y     := mkcpustr tools/build
+hostprogs-y     := tools/build
+hostprogs-$(CONFIG_X86_FEATURE_NAMES) += mkcpustr
 
 HOST_EXTRACFLAGS += -I$(srctree)/tools/include \
                     -include include/generated/autoconf.h \
                     -D__EXPORTED_HEADERS__
 
+ifdef CONFIG_X86_FEATURE_NAMES
 $(obj)/cpu.o: $(obj)/cpustr.h
 
 quiet_cmd_cpustr = CPUSTR  $@
       cmd_cpustr = $(obj)/mkcpustr > $@
-targets         += cpustr.h
+targets += cpustr.h
 $(obj)/cpustr.h: $(obj)/mkcpustr FORCE
         $(call if_changed,cpustr)
+endif
 
 # ---------------------------------------------------------------------------
 
diff --git a/arch/x86/boot/cpu.c b/arch/x86/boot/cpu.c
index 6ec6bb6e9957..29207f69ae8c 100644
--- a/arch/x86/boot/cpu.c
+++ b/arch/x86/boot/cpu.c
@@ -16,7 +16,9 @@
  */
 
 #include "boot.h"
+#ifdef CONFIG_X86_FEATURE_NAMES
 #include "cpustr.h"
+#endif
 
 static char *cpu_name(int level)
 {
@@ -32,11 +34,48 @@ static char *cpu_name(int level)
         }
 }
 
+static void show_cap_strs(u32 *err_flags)
+{
+        int i, j;
+#ifdef CONFIG_X86_FEATURE_NAMES
+        const unsigned char *msg_strs = (const unsigned char *)x86_cap_strs;
+        for (i = 0; i < NCAPINTS; i++) {
+                u32 e = err_flags[i];
+                for (j = 0; j < 32; j++) {
+                        if (msg_strs[0] < i ||
+                            (msg_strs[0] == i && msg_strs[1] < j)) {
+                                /* Skip to the next string */
+                                msg_strs += 2;
+                                while (*msg_strs++)
+                                        ;
+                        }
+                        if (e & 1) {
+                                if (msg_strs[0] == i &&
+                                    msg_strs[1] == j &&
+                                    msg_strs[2])
+                                        printf("%s ", msg_strs+2);
+                                else
+                                        printf("%d:%d ", i, j);
+                        }
+                        e >>= 1;
+                }
+        }
+#else
+        for (i = 0; i < NCAPINTS; i++) {
+                u32 e = err_flags[i];
+                for (j = 0; j < 32; j++) {
+                        if (e & 1)
+                                printf("%d:%d ", i, j);
+                        e >>= 1;
+                }
+        }
+#endif
+}
+
 int validate_cpu(void)
 {
         u32 *err_flags;
         int cpu_level, req_level;
-        const unsigned char *msg_strs;
 
         check_cpu(&cpu_level, &req_level, &err_flags);
 
@@ -49,34 +88,9 @@ int validate_cpu(void)
         }
 
         if (err_flags) {
-                int i, j;
                 puts("This kernel requires the following features "
                      "not present on the CPU:\n");
-
-                msg_strs = (const unsigned char *)x86_cap_strs;
-
-                for (i = 0; i < NCAPINTS; i++) {
-                        u32 e = err_flags[i];
-
-                        for (j = 0; j < 32; j++) {
-                                if (msg_strs[0] < i ||
-                                    (msg_strs[0] == i && msg_strs[1] < j)) {
-                                        /* Skip to the next string */
-                                        msg_strs += 2;
-                                        while (*msg_strs++)
-                                                ;
-                                }
-                                if (e & 1) {
-                                        if (msg_strs[0] == i &&
-                                            msg_strs[1] == j &&
-                                            msg_strs[2])
-                                                printf("%s ", msg_strs+2);
-                                        else
-                                                printf("%d:%d ", i, j);
-                                }
-                                e >>= 1;
-                        }
-                }
+                show_cap_strs(err_flags);
                 putchar('\n');
                 return -1;
         } else {