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>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5d0bf1aa9dcb6d68fd39f395dcbef9f89954cbc0..a11f27c4266a6758387b9bd9643cd8819ee22c2c 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -136,6 +136,7 @@ config X86
        select HAVE_ACPI_APEI if ACPI
        select HAVE_ACPI_APEI_NMI if ACPI
        select ACPI_LEGACY_TABLES_LOOKUP if ACPI
+       select X86_FEATURE_NAMES if PROC_FS
 
 config INSTRUCTION_DECODER
        def_bool y
@@ -313,6 +314,17 @@ config SMP
 
          If you don't know what to do here, say N.
 
+config X86_FEATURE_NAMES
+       bool "Processor feature human-readable names" if EMBEDDED
+       default y
+       ---help---
+         This option compiles in a table of x86 feature bits and corresponding
+         names.  This is required to support /proc/cpuinfo and a few kernel
+         messages.  You can disable this to save space, at the expense of
+         making those few kernel messages show numeric feature bits instead.
+
+         If in doubt, say Y.
+
 config X86_X2APIC
        bool "Support x2apic"
        depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index dbe8dd2fe247fb0632a79d5a20d1b4714729c47d..5b016e2498f3d3250b4edf12584a524bcb79e968 100644 (file)
--- 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 6ec6bb6e9957a0319259f966c0ac7b2ca4ff69a0..29207f69ae8c760837984307b51afcf5377c1b49 100644 (file)
--- 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 {

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index bb9b258d60e76e9c3dfc3cefe8c7f74ac80e3caf..516903b98e06f5d9c20be87e07231a682714d287 100644 (file)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -250,8 +250,15 @@
 #include <asm/asm.h>
 #include <linux/bitops.h>
 
+#ifdef CONFIG_X86_FEATURE_NAMES
 extern const char * const x86_cap_flags[NCAPINTS*32];
 extern const char * const x86_power_flags[32];
+#define X86_CAP_FMT "%s"
+#define x86_cap_flag(flag) x86_cap_flags[flag]
+#else
+#define X86_CAP_FMT "%d:%d"
+#define x86_cap_flag(flag) ((flag) >> 5), ((flag) & 31)
+#endif
 
 /*
  * In order to save room, we index into this array by doing

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 64038d842c57fe6451b2ea03f92f6470b43481ea..77dcab277710763cc0e6cc7ceb9a3fb8ef0b8c57 100644 (file)
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -13,11 +13,12 @@ nostackp := $(call cc-option, -fno-stack-protector)
 CFLAGS_common.o                := $(nostackp)
 
 obj-y                  := intel_cacheinfo.o scattered.o topology.o
-obj-y                  += capflags.o powerflags.o common.o
+obj-y                  += common.o
 obj-y                  += rdrand.o
 obj-y                  += match.o
 
 obj-$(CONFIG_PROC_FS)  += proc.o
+obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o
 
 obj-$(CONFIG_X86_32)   += bugs.o
 obj-$(CONFIG_X86_64)   += bugs_64.o
@@ -50,6 +51,7 @@ obj-$(CONFIG_X86_LOCAL_APIC)          += perfctr-watchdog.o perf_event_amd_ibs.o
 
 obj-$(CONFIG_HYPERVISOR_GUEST)         += vmware.o hypervisor.o mshyperv.o
 
+ifdef CONFIG_X86_FEATURE_NAMES
 quiet_cmd_mkcapflags = MKCAP   $@
       cmd_mkcapflags = $(CONFIG_SHELL) $(srctree)/$(src)/mkcapflags.sh $< $@
 
@@ -58,3 +60,4 @@ cpufeature = $(src)/../../include/asm/cpufeature.h
 targets += capflags.c
 $(obj)/capflags.c: $(cpufeature) $(src)/mkcapflags.sh FORCE
        $(call if_changed,mkcapflags)
+endif

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index e4ab2b42bd6f469528c73cac4ac0fb186b5bdbd3..c649f236e288849f94f8b2bf4501117cd2f1a698 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -346,8 +346,8 @@ static void filter_cpuid_features(struct cpuinfo_x86 *c, bool warn)
                        continue;
 
                printk(KERN_WARNING
-                      "CPU: CPU feature %s disabled, no CPUID level 0x%x\n",
-                               x86_cap_flags[df->feature], df->level);
+                      "CPU: CPU feature " X86_CAP_FMT " disabled, no CPUID level 0x%x\n",
+                               x86_cap_flag(df->feature), df->level);
        }
 }