x86, msr: Unify rdmsr_on_cpus/wrmsr_on_cpus
[linux-2.6-block.git] / arch / x86 / Kconfig.cpu
CommitLineData
96d55b88
PBG
1# Put here option for CPU selection and depending optimization
2if !X86_ELAN
3
4choice
5 prompt "Processor family"
1032c0ba
SR
6 default M686 if X86_32
7 default GENERIC_CPU if X86_64
96d55b88
PBG
8
9config M386
10 bool "386"
1032c0ba 11 depends on X86_32 && !UML
96d55b88
PBG
12 ---help---
13 This is the processor type of your CPU. This information is used for
14 optimizing purposes. In order to compile a kernel that can run on
15 all x86 CPU types (albeit not optimally fast), you can specify
16 "386" here.
17
18 The kernel will not necessarily run on earlier architectures than
19 the one you have chosen, e.g. a Pentium optimized kernel will run on
20 a PPro, but not necessarily on a i486.
21
22 Here are the settings recommended for greatest speed:
23 - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
f7f17a67
DV
24 486DLC/DLC2, and UMC 486SX-S. Only "386" kernels will run on a 386
25 class machine.
96d55b88
PBG
26 - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
27 SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
28 - "586" for generic Pentium CPUs lacking the TSC
29 (time stamp counter) register.
30 - "Pentium-Classic" for the Intel Pentium.
31 - "Pentium-MMX" for the Intel Pentium MMX.
32 - "Pentium-Pro" for the Intel Pentium Pro.
33 - "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.
34 - "Pentium-III" for the Intel Pentium III or Coppermine Celeron.
35 - "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
36 - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
37 - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
38 - "Crusoe" for the Transmeta Crusoe series.
39 - "Efficeon" for the Transmeta Efficeon series.
40 - "Winchip-C6" for original IDT Winchip.
69d45dd1 41 - "Winchip-2" for IDT Winchips with 3dNow! capabilities.
96d55b88 42 - "GeodeGX1" for Geode GX1 (Cyrix MediaGX).
f90b8116 43 - "Geode GX/LX" For AMD Geode GX and LX processors.
96d55b88 44 - "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
48a1204c 45 - "VIA C3-2" for VIA C3-2 "Nehemiah" (model 9 and above).
0949be35 46 - "VIA C7" for VIA C7.
96d55b88
PBG
47
48 If you don't know what to do, choose "386".
49
50config M486
51 bool "486"
1032c0ba 52 depends on X86_32
8f9ca475 53 ---help---
96d55b88
PBG
54 Select this for a 486 series processor, either Intel or one of the
55 compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,
56 DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
57 U5S.
58
59config M586
60 bool "586/K5/5x86/6x86/6x86MX"
1032c0ba 61 depends on X86_32
8f9ca475 62 ---help---
96d55b88
PBG
63 Select this for an 586 or 686 series processor such as the AMD K5,
64 the Cyrix 5x86, 6x86 and 6x86MX. This choice does not
65 assume the RDTSC (Read Time Stamp Counter) instruction.
66
67config M586TSC
68 bool "Pentium-Classic"
1032c0ba 69 depends on X86_32
8f9ca475 70 ---help---
96d55b88
PBG
71 Select this for a Pentium Classic processor with the RDTSC (Read
72 Time Stamp Counter) instruction for benchmarking.
73
74config M586MMX
75 bool "Pentium-MMX"
1032c0ba 76 depends on X86_32
8f9ca475 77 ---help---
96d55b88
PBG
78 Select this for a Pentium with the MMX graphics/multimedia
79 extended instructions.
80
81config M686
82 bool "Pentium-Pro"
1032c0ba 83 depends on X86_32
8f9ca475 84 ---help---
96d55b88
PBG
85 Select this for Intel Pentium Pro chips. This enables the use of
86 Pentium Pro extended instructions, and disables the init-time guard
87 against the f00f bug found in earlier Pentiums.
88
89config MPENTIUMII
90 bool "Pentium-II/Celeron(pre-Coppermine)"
1032c0ba 91 depends on X86_32
8f9ca475 92 ---help---
96d55b88
PBG
93 Select this for Intel chips based on the Pentium-II and
94 pre-Coppermine Celeron core. This option enables an unaligned
95 copy optimization, compiles the kernel with optimization flags
96 tailored for the chip, and applies any applicable Pentium Pro
97 optimizations.
98
99config MPENTIUMIII
100 bool "Pentium-III/Celeron(Coppermine)/Pentium-III Xeon"
1032c0ba 101 depends on X86_32
8f9ca475 102 ---help---
96d55b88
PBG
103 Select this for Intel chips based on the Pentium-III and
104 Celeron-Coppermine core. This option enables use of some
105 extended prefetch instructions in addition to the Pentium II
106 extensions.
107
108config MPENTIUMM
109 bool "Pentium M"
1032c0ba 110 depends on X86_32
8f9ca475 111 ---help---
96d55b88
PBG
112 Select this for Intel Pentium M (not Pentium-4 M)
113 notebook chips.
114
115config MPENTIUM4
c55d92d1 116 bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/older Xeon"
1032c0ba 117 depends on X86_32
8f9ca475 118 ---help---
96d55b88 119 Select this for Intel Pentium 4 chips. This includes the
75e3808b
OP
120 Pentium 4, Pentium D, P4-based Celeron and Xeon, and
121 Pentium-4 M (not Pentium M) chips. This option enables compile
122 flags optimized for the chip, uses the correct cache line size, and
123 applies any applicable optimizations.
124
125 CPUIDs: F[0-6][1-A] (in /proc/cpuinfo show = cpu family : 15 )
126
127 Select this for:
128 Pentiums (Pentium 4, Pentium D, Celeron, Celeron D) corename:
129 -Willamette
130 -Northwood
131 -Mobile Pentium 4
132 -Mobile Pentium 4 M
133 -Extreme Edition (Gallatin)
134 -Prescott
135 -Prescott 2M
136 -Cedar Mill
137 -Presler
138 -Smithfiled
139 Xeons (Intel Xeon, Xeon MP, Xeon LV, Xeon MV) corename:
140 -Foster
141 -Prestonia
142 -Gallatin
143 -Nocona
144 -Irwindale
145 -Cranford
146 -Potomac
147 -Paxville
148 -Dempsey
149
96d55b88
PBG
150
151config MK6
152 bool "K6/K6-II/K6-III"
1032c0ba 153 depends on X86_32
8f9ca475 154 ---help---
96d55b88
PBG
155 Select this for an AMD K6-family processor. Enables use of
156 some extended instructions, and passes appropriate optimization
157 flags to GCC.
158
159config MK7
160 bool "Athlon/Duron/K7"
1032c0ba 161 depends on X86_32
8f9ca475 162 ---help---
96d55b88
PBG
163 Select this for an AMD Athlon K7-family processor. Enables use of
164 some extended instructions, and passes appropriate optimization
165 flags to GCC.
166
167config MK8
168 bool "Opteron/Athlon64/Hammer/K8"
8f9ca475 169 ---help---
36723bfe
BP
170 Select this for an AMD Opteron or Athlon64 Hammer-family processor.
171 Enables use of some extended instructions, and passes appropriate
172 optimization flags to GCC.
96d55b88
PBG
173
174config MCRUSOE
175 bool "Crusoe"
1032c0ba 176 depends on X86_32
8f9ca475 177 ---help---
96d55b88
PBG
178 Select this for a Transmeta Crusoe processor. Treats the processor
179 like a 586 with TSC, and sets some GCC optimization flags (like a
180 Pentium Pro with no alignment requirements).
181
182config MEFFICEON
183 bool "Efficeon"
1032c0ba 184 depends on X86_32
8f9ca475 185 ---help---
96d55b88
PBG
186 Select this for a Transmeta Efficeon processor.
187
188config MWINCHIPC6
189 bool "Winchip-C6"
1032c0ba 190 depends on X86_32
8f9ca475 191 ---help---
96d55b88
PBG
192 Select this for an IDT Winchip C6 chip. Linux and GCC
193 treat this chip as a 586TSC with some extended instructions
194 and alignment requirements.
195
96d55b88 196config MWINCHIP3D
69d45dd1 197 bool "Winchip-2/Winchip-2A/Winchip-3"
1032c0ba 198 depends on X86_32
8f9ca475 199 ---help---
69d45dd1 200 Select this for an IDT Winchip-2, 2A or 3. Linux and GCC
96d55b88 201 treat this chip as a 586TSC with some extended instructions
3dde6ad8 202 and alignment requirements. Also enable out of order memory
96d55b88
PBG
203 stores for this CPU, which can increase performance of some
204 operations.
205
206config MGEODEGX1
207 bool "GeodeGX1"
1032c0ba 208 depends on X86_32
8f9ca475 209 ---help---
96d55b88
PBG
210 Select this for a Geode GX1 (Cyrix MediaGX) chip.
211
f90b8116 212config MGEODE_LX
96daa8cd 213 bool "Geode GX/LX"
1032c0ba 214 depends on X86_32
8f9ca475 215 ---help---
96daa8cd 216 Select this for AMD Geode GX and LX processors.
f90b8116 217
96d55b88
PBG
218config MCYRIXIII
219 bool "CyrixIII/VIA-C3"
1032c0ba 220 depends on X86_32
8f9ca475 221 ---help---
96d55b88
PBG
222 Select this for a Cyrix III or C3 chip. Presently Linux and GCC
223 treat this chip as a generic 586. Whilst the CPU is 686 class,
224 it lacks the cmov extension which gcc assumes is present when
225 generating 686 code.
226 Note that Nehemiah (Model 9) and above will not boot with this
227 kernel due to them lacking the 3DNow! instructions used in earlier
228 incarnations of the CPU.
229
230config MVIAC3_2
231 bool "VIA C3-2 (Nehemiah)"
1032c0ba 232 depends on X86_32
8f9ca475 233 ---help---
96d55b88
PBG
234 Select this for a VIA C3 "Nehemiah". Selecting this enables usage
235 of SSE and tells gcc to treat the CPU as a 686.
236 Note, this kernel will not boot on older (pre model 9) C3s.
237
0949be35
SA
238config MVIAC7
239 bool "VIA C7"
1032c0ba 240 depends on X86_32
8f9ca475 241 ---help---
0949be35
SA
242 Select this for a VIA C7. Selecting this uses the correct cache
243 shift and tells gcc to treat the CPU as a 686.
244
1032c0ba
SR
245config MPSC
246 bool "Intel P4 / older Netburst based Xeon"
247 depends on X86_64
8f9ca475 248 ---help---
1032c0ba
SR
249 Optimize for Intel Pentium 4, Pentium D and older Nocona/Dempsey
250 Xeon CPUs with Intel 64bit which is compatible with x86-64.
251 Note that the latest Xeons (Xeon 51xx and 53xx) are not based on the
96daa8cd 252 Netburst core and shouldn't use this option. You can distinguish them
1032c0ba
SR
253 using the cpu family field
254 in /proc/cpuinfo. Family 15 is an older Xeon, Family 6 a newer one.
255
256config MCORE2
257 bool "Core 2/newer Xeon"
8f9ca475 258 ---help---
36723bfe
BP
259
260 Select this for Intel Core 2 and newer Core 2 Xeons (Xeon 51xx and
261 53xx) CPUs. You can distinguish newer from older Xeons by the CPU
262 family in /proc/cpuinfo. Newer ones have 6 and older ones 15
263 (not a typo)
1032c0ba 264
366d19e1
TD
265config MATOM
266 bool "Intel Atom"
267 ---help---
268
269 Select this for the Intel Atom platform. Intel Atom CPUs have an
270 in-order pipelining architecture and thus can benefit from
271 accordingly optimized code. Use a recent GCC with specific Atom
272 support in order to fully benefit from selecting this option.
273
1032c0ba
SR
274config GENERIC_CPU
275 bool "Generic-x86-64"
276 depends on X86_64
8f9ca475 277 ---help---
1032c0ba
SR
278 Generic x86-64 CPU.
279 Run equally well on all x86-64 CPUs.
280
96d55b88
PBG
281endchoice
282
283config X86_GENERIC
1032c0ba
SR
284 bool "Generic x86 support"
285 depends on X86_32
8f9ca475 286 ---help---
96d55b88
PBG
287 Instead of just including optimizations for the selected
288 x86 variant (e.g. PII, Crusoe or Athlon), include some more
289 generic optimizations as well. This will make the kernel
290 perform better on x86 CPUs other than that selected.
291
292 This is really intended for distributors who need more
293 generic optimizations.
294
295endif
296
acbaa93e
IM
297config X86_CPU
298 def_bool y
299 select GENERIC_FIND_FIRST_BIT
300 select GENERIC_FIND_NEXT_BIT
301
96d55b88
PBG
302#
303# Define implied options from the CPU selection here
1032c0ba
SR
304config X86_L1_CACHE_BYTES
305 int
ace6c6c8 306 default "128" if MPSC
366d19e1 307 default "64" if GENERIC_CPU || MK8 || MCORE2 || MATOM || X86_32
1032c0ba
SR
308
309config X86_INTERNODE_CACHE_BYTES
310 int
311 default "4096" if X86_VSMP
312 default X86_L1_CACHE_BYTES if !X86_VSMP
1032c0ba 313
96d55b88 314config X86_CMPXCHG
1032c0ba 315 def_bool X86_64 || (X86_32 && !M386)
96d55b88 316
96d55b88
PBG
317config X86_L1_CACHE_SHIFT
318 int
0a2a18b7 319 default "7" if MPENTIUM4 || MPSC
f90b8116 320 default "4" if X86_ELAN || M486 || M386 || MGEODEGX1
69d45dd1 321 default "5" if MWINCHIP3D || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 || MGEODE_LX
366d19e1 322 default "6" if MK7 || MK8 || MPENTIUMM || MCORE2 || MATOM || MVIAC7 || X86_GENERIC || GENERIC_CPU
96d55b88 323
c7f81c94 324config X86_XADD
96daa8cd 325 def_bool y
1032c0ba 326 depends on X86_32 && !M386
96d55b88
PBG
327
328config X86_PPRO_FENCE
fb0328e2 329 bool "PentiumPro memory ordering errata workaround"
96d55b88 330 depends on M686 || M586MMX || M586TSC || M586 || M486 || M386 || MGEODEGX1
8f9ca475 331 ---help---
36723bfe
BP
332 Old PentiumPro multiprocessor systems had errata that could cause
333 memory operations to violate the x86 ordering standard in rare cases.
334 Enabling this option will attempt to work around some (but not all)
335 occurances of this problem, at the cost of much heavier spinlock and
336 memory barrier operations.
337
338 If unsure, say n here. Even distro kernels should think twice before
339 enabling this: there are few systems, and an unlikely bug.
96d55b88
PBG
340
341config X86_F00F_BUG
96daa8cd 342 def_bool y
96d55b88 343 depends on M586MMX || M586TSC || M586 || M486 || M386
96d55b88
PBG
344
345config X86_WP_WORKS_OK
96daa8cd 346 def_bool y
293e6a25 347 depends on !M386
96d55b88
PBG
348
349config X86_INVLPG
96daa8cd 350 def_bool y
1032c0ba 351 depends on X86_32 && !M386
96d55b88
PBG
352
353config X86_BSWAP
96daa8cd 354 def_bool y
1032c0ba 355 depends on X86_32 && !M386
96d55b88
PBG
356
357config X86_POPAD_OK
96daa8cd 358 def_bool y
1032c0ba 359 depends on X86_32 && !M386
96d55b88 360
96d55b88 361config X86_ALIGNMENT_16
96daa8cd 362 def_bool y
69d45dd1 363 depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
96d55b88 364
96d55b88 365config X86_INTEL_USERCOPY
96daa8cd 366 def_bool y
c55d92d1 367 depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON || MCORE2
96d55b88
PBG
368
369config X86_USE_PPRO_CHECKSUM
96daa8cd 370 def_bool y
366d19e1 371 depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MEFFICEON || MGEODE_LX || MCORE2 || MATOM
96d55b88
PBG
372
373config X86_USE_3DNOW
96daa8cd 374 def_bool y
1b4ad242 375 depends on (MCYRIXIII || MK7 || MGEODE_LX) && !UML
96d55b88
PBG
376
377config X86_OOSTORE
96daa8cd 378 def_bool y
69d45dd1 379 depends on (MWINCHIP3D || MWINCHIPC6) && MTRR
96d55b88 380
959b3be6
PA
381#
382# P6_NOPs are a relatively minor optimization that require a family >=
383# 6 processor, except that it is broken on certain VIA chips.
384# Furthermore, AMD chips prefer a totally different sequence of NOPs
14469a8d
LT
385# (which work on all CPUs). In addition, it looks like Virtual PC
386# does not understand them.
387#
388# As a result, disallow these if we're not compiling for X86_64 (these
389# NOPs do work on all x86-64 capable chips); the list of processors in
390# the right-hand clause are the cores that benefit from this optimization.
959b3be6 391#
7343b3b3
PA
392config X86_P6_NOP
393 def_bool y
14469a8d
LT
394 depends on X86_64
395 depends on (MCORE2 || MPENTIUM4 || MPSC)
7343b3b3 396
96d55b88 397config X86_TSC
96daa8cd 398 def_bool y
366d19e1 399 depends on ((MWINCHIP3D || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MVIAC7 || MGEODEGX1 || MGEODE_LX || MCORE2 || MATOM) && !X86_NUMAQ) || X86_64
c7f81c94 400
f8096f92
JB
401config X86_CMPXCHG64
402 def_bool y
403 depends on X86_PAE || X86_64
404
c7f81c94
AK
405# this should be set for all -march=.. options where the compiler
406# generates cmov.
407config X86_CMOV
96daa8cd 408 def_bool y
366d19e1 409 depends on (MK8 || MK7 || MCORE2 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7 || MCRUSOE || MEFFICEON || X86_64 || MATOM)
c7f81c94 410
de32e041 411config X86_MINIMUM_CPU_FAMILY
c7f81c94 412 int
1032c0ba 413 default "64" if X86_64
7343b3b3 414 default "6" if X86_32 && X86_P6_NOP
1032c0ba 415 default "4" if X86_32 && (X86_XADD || X86_CMPXCHG || X86_BSWAP || X86_WP_WORKS_OK)
de32e041 416 default "3"
c7f81c94 417
0a049bb0 418config X86_DEBUGCTLMSR
96daa8cd 419 def_bool y
5641f1fd 420 depends on !(MK6 || MWINCHIPC6 || MWINCHIP3D || MCYRIXIII || M586MMX || M586TSC || M586 || M486 || M386) && !UML
8d02c211
TP
421
422menuconfig PROCESSOR_SELECT
8d02c211 423 bool "Supported processor vendors" if EMBEDDED
8f9ca475 424 ---help---
8d02c211
TP
425 This lets you choose what x86 vendor support code your kernel
426 will include.
427
879d792b 428config CPU_SUP_INTEL
8d02c211
TP
429 default y
430 bool "Support Intel processors" if PROCESSOR_SELECT
8f9ca475 431 ---help---
b7b3a425
IM
432 This enables detection, tunings and quirks for Intel processors
433
434 You need this enabled if you want your kernel to run on an
435 Intel CPU. Disabling this option on other types of CPUs
436 makes the kernel a tiny bit smaller. Disabling it on an Intel
437 CPU might render the kernel unbootable.
438
439 If unsure, say N.
8d02c211
TP
440
441config CPU_SUP_CYRIX_32
442 default y
443 bool "Support Cyrix processors" if PROCESSOR_SELECT
444 depends on !64BIT
8f9ca475 445 ---help---
b7b3a425
IM
446 This enables detection, tunings and quirks for Cyrix processors
447
448 You need this enabled if you want your kernel to run on a
449 Cyrix CPU. Disabling this option on other types of CPUs
450 makes the kernel a tiny bit smaller. Disabling it on a Cyrix
451 CPU might render the kernel unbootable.
452
453 If unsure, say N.
8d02c211 454
ff73152c 455config CPU_SUP_AMD
8d02c211
TP
456 default y
457 bool "Support AMD processors" if PROCESSOR_SELECT
8f9ca475 458 ---help---
b7b3a425
IM
459 This enables detection, tunings and quirks for AMD processors
460
461 You need this enabled if you want your kernel to run on an
462 AMD CPU. Disabling this option on other types of CPUs
463 makes the kernel a tiny bit smaller. Disabling it on an AMD
464 CPU might render the kernel unbootable.
465
466 If unsure, say N.
8d02c211 467
48f4c485 468config CPU_SUP_CENTAUR
8d02c211
TP
469 default y
470 bool "Support Centaur processors" if PROCESSOR_SELECT
8f9ca475 471 ---help---
b7b3a425
IM
472 This enables detection, tunings and quirks for Centaur processors
473
474 You need this enabled if you want your kernel to run on a
475 Centaur CPU. Disabling this option on other types of CPUs
476 makes the kernel a tiny bit smaller. Disabling it on a Centaur
477 CPU might render the kernel unbootable.
478
479 If unsure, say N.
8d02c211
TP
480
481config CPU_SUP_TRANSMETA_32
482 default y
483 bool "Support Transmeta processors" if PROCESSOR_SELECT
484 depends on !64BIT
8f9ca475 485 ---help---
b7b3a425
IM
486 This enables detection, tunings and quirks for Transmeta processors
487
488 You need this enabled if you want your kernel to run on a
489 Transmeta CPU. Disabling this option on other types of CPUs
490 makes the kernel a tiny bit smaller. Disabling it on a Transmeta
491 CPU might render the kernel unbootable.
492
493 If unsure, say N.
8d02c211
TP
494
495config CPU_SUP_UMC_32
496 default y
497 bool "Support UMC processors" if PROCESSOR_SELECT
498 depends on !64BIT
8f9ca475 499 ---help---
b7b3a425
IM
500 This enables detection, tunings and quirks for UMC processors
501
502 You need this enabled if you want your kernel to run on a
503 UMC CPU. Disabling this option on other types of CPUs
504 makes the kernel a tiny bit smaller. Disabling it on a UMC
505 CPU might render the kernel unbootable.
506
507 If unsure, say N.
81faaae4 508
93fa7636 509config X86_DS
531f6ed7
MM
510 def_bool X86_PTRACE_BTS
511 depends on X86_DEBUGCTLMSR
1e9b51c2 512 select HAVE_HW_BRANCH_TRACER
93fa7636
MM
513
514config X86_PTRACE_BTS
531f6ed7 515 bool "Branch Trace Store"
93fa7636 516 default y
531f6ed7 517 depends on X86_DEBUGCTLMSR
d45b41ae 518 depends on BROKEN
8f9ca475 519 ---help---
531f6ed7
MM
520 This adds a ptrace interface to the hardware's branch trace store.
521
522 Debuggers may use it to collect an execution trace of the debugged
523 application in order to answer the question 'how did I get here?'.
524 Debuggers may trace user mode as well as kernel mode.
525
526 Say Y unless there is no application development on this machine
527 and you want to save a small amount of code size.