Hi all,

I find the below WARNING shows up only in

        qemu-system-x86_64 -cpu qemu64,+smep,+smap

[    0.018000] Initializing CPU#1
[    0.018000] masked ExtINT on CPU#1
[    0.018000] ------------[ cut here ]------------
[    0.018000] WARNING: CPU: 1 PID: 0 at arch/x86/kernel/cpu/amd.c:220 init_amd+0x752/0x780()
[    0.018000] WARNING: This combination of AMD processors is not suitable for SMP.          
[    0.018000] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.14.0-rc3-next-20140221-04488-gfaa2e6f #1
[    0.018000]  00000000 00000000 80047ec0 8a1c529a 80047f00 80047ef0 89c44b6f 8a38b9f4            
[    0.018000]  80047f1c 00000000 8a38ba3c 000000dc 89c124a2 89c124a2 9396cfc0 9396d010
[    0.018000]  9396d03c 80047f08 89c44bee 00000009 80047f00 8a38b9f4 80047f1c 80047f44
[    0.018000] Call Trace:
[    0.018000]  [<8a1c529a>] dump_stack+0x48/0x60
[    0.018000]  [<89c44b6f>] warn_slowpath_common+0x6f/0x90
[    0.018000]  [<89c124a2>] ? init_amd+0x752/0x780
[    0.018000]  [<89c124a2>] ? init_amd+0x752/0x780
[    0.018000]  [<89c44bee>] warn_slowpath_fmt+0x2e/0x30
[    0.018000]  [<89c124a2>] init_amd+0x752/0x780
[    0.018000]  [<89c104a7>] identify_cpu+0x117/0x4d0
[    0.018000]  [<89c1086f>] identify_secondary_cpu+0xf/0x20
[    0.018000]  [<89c289ed>] smp_store_cpu_info+0x2d/0x40   
[    0.018000]  [<89c290ac>] start_secondary+0xec/0x270
[    0.018000] ---[ end trace 129d9276306a64a7 ]---

Bisect shows that it predates Linux 3.0:

git bisect good faa2e6fb0a98c9caa8995acf3222db9f7f029395  # 05:42     10+     17  Add linux-next specific files for 20140221
git bisect  bad faa2e6fb0a98c9caa8995acf3222db9f7f029395  # 05:45      8-     20  Add linux-next specific files for 20140221
git bisect  bad 5047a5b231a24b15d06958cefb54858d77debd22  # 05:46      0-     10  Merge remote-tracking branch 'llvmlinux/for-next'
git bisect  bad d8ec26d7f8287f5788a494f56e8814210f0e64be  # 05:46      0-      7  Linux 3.13
git bisect  bad 5e01dc7b26d9f24f39abace5da98ccbd6a5ceb52  # 05:46      0-     16  Linux 3.12
git bisect  bad 6e4664525b1db28f8c4e1130957f70a94c19213e  # 05:46      0-     74  Linux 3.11
git bisect  bad 8bb495e3f02401ee6f76d1b1d77f3ac9f079e376  # 05:46      0-     77  Linux 3.10
git bisect  bad c1be5a5b1b355d40e6cf79cc979eb66dafa24ad1  # 05:53     42-      2  Linux 3.9
git bisect  bad 19f949f52599ba7c3f67a5897ac6be14bfcb1200  # 05:57      2-      3  Linux 3.8
git bisect  bad 29594404d7fe73cd80eaa4ee8c43dcc53970c60e  # 06:18    125-     64  Linux 3.7
git bisect  bad a0d271cbfed1dd50278c6b06bead3d00ba0a88f9  # 06:26     35-     20  Linux 3.6
git bisect  bad 28a33cbc24e4256c143dce96c7d93bf423229f92  # 06:30      6-      5  Linux 3.5
git bisect  bad 76e10d158efb6d4516018846f60c2ab5501900bc  # 06:36     62-     39  Linux 3.4
git bisect  bad c16fa4f2ad19908a47c63d8fa436a1178438c7e7  # 06:46     87-     33  Linux 3.3
git bisect  bad 805a6af8dba5dfdd35ec35dc52ec0122400b2610  # 06:52     23-     10  Linux 3.2
git bisect  bad c3b92c8787367a8bb53d57d9789b558f1295cc96  # 07:14    525-    201  Linux 3.1
git bisect  bad 02f8c6aee8df3cdc935e9bdd4f2d020306035dbe  # 07:29    248-    105  Linux 3.0

Thanks,
Fengguang