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Date: Sat, 22 Feb 2014 11:19:18 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Josh Triplett <josh@...htriplett.org>,
Andi Kleen <ak@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Borislav Petkov <bp@...e.de>, Feng Tang <feng.tang@...el.com>,
Ingo Molnar <mingo@...hat.com>,
Jacob Shin <jacob.shin@....com>,
Jan Beulich <JBeulich@...e.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Peter Zijlstra <peterz@...radead.org>,
Qiaowei Ren <qiaowei.ren@...el.com>,
Rob Landley <rob@...dley.net>,
Seiji Aguchi <seiji.aguchi@....com>,
Stephane Eranian <eranian@...gle.com>,
Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Thomas Renninger <trenn@...e.de>, linux-kernel@...r.kernel.org,
x86@...nel.org
Subject: Re: [PATCH 2/2] x86: Support compiling out human-friendly processor feature names
Also, for the numeric message at least please show it in word:bit format.
On February 22, 2014 11:09:30 AM PST, Josh Triplett <josh@...htriplett.org> wrote:
>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@...htriplett.org>
>---
> arch/x86/Kconfig | 12 +++++++
> arch/x86/boot/Makefile | 5 ++-
>arch/x86/boot/cpu.c | 68
>+++++++++++++++++++++++----------------
> arch/x86/include/asm/cpufeature.h | 13 ++++++++
> arch/x86/kernel/cpu/Makefile | 5 ++-
> arch/x86/kernel/cpu/common.c | 4 +--
> 6 files changed, 76 insertions(+), 31 deletions(-)
>
>diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>index 0af5250..4dfdbdc 100644
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -127,6 +127,7 @@ config X86
> select HAVE_DEBUG_STACKOVERFLOW
> select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
> select HAVE_CC_STACKPROTECTOR
>+ select X86_FEATURE_NAMES if PROC_FS
>
> config INSTRUCTION_DECODER
> def_bool y
>@@ -304,6 +305,17 @@ config SMP
>
> If you don't know what to do here, say N.
>
>+config X86_FEATURE_NAMES
>+ bool "Processor feature human-readable names"
>+ 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 878df7e..ca6f7ed 100644
>--- a/arch/x86/boot/Makefile
>+++ b/arch/x86/boot/Makefile
>@@ -35,7 +35,7 @@ setup-y += video-vesa.o
> setup-y += video-bios.o
>
> targets += $(setup-y)
>-hostprogs-y := mkcpustr tools/build
>+hostprogs-y := tools/build
>
> HOST_EXTRACFLAGS += -I$(srctree)/tools/include \
> -include include/generated/autoconf.h \
>@@ -43,11 +43,14 @@ HOST_EXTRACFLAGS += -I$(srctree)/tools/include \
>
> $(obj)/cpu.o: $(obj)/cpustr.h
>
>+ifdef CONFIG_X86_FEATURE_NAMES
>+hostprogs-y += mkcpustr
> quiet_cmd_cpustr = CPUSTR $@
> cmd_cpustr = $(obj)/mkcpustr > $@
> 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 6ec6bb6..29207f6 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 {
>diff --git a/arch/x86/include/asm/cpufeature.h
>b/arch/x86/include/asm/cpufeature.h
>index e099f95..af6d7d5 100644
>--- a/arch/x86/include/asm/cpufeature.h
>+++ b/arch/x86/include/asm/cpufeature.h
>@@ -237,8 +237,21 @@
> #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"
>+static inline const char *x86_cap_flag(u32 flag)
>+{
>+ return x86_cap_flags[flag];
>+}
>+#else
>+#define X86_CAP_FMT "%x"
>+static inline u32 x86_cap_flag(u32 flag)
>+{
>+ return flag;
>+}
>+#endif
>
> #define test_cpu_cap(c, bit) \
> test_bit(bit, (unsigned long *)((c)->x86_capability))
>diff --git a/arch/x86/kernel/cpu/Makefile
>b/arch/x86/kernel/cpu/Makefile
>index 64038d8..77dcab2 100644
>--- 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 8e28bf2..3991a81 100644
>--- a/arch/x86/kernel/cpu/common.c
>+++ b/arch/x86/kernel/cpu/common.c
>@@ -336,8 +336,8 @@ 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);
> }
> }
>
--
Sent from my mobile phone. Please pardon brevity and lack of formatting.
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