Am 14.02.19 um 22:46 schrieb Jan H. Schönherr:
Some systems experience regular interruptions (60 Hz SMI?), that prevent
the quick PIT calibration from succeeding: individual interruptions can be
so long, that the PIT MSB is observed to decrement by 2 or 3 instead of 1.
The existing code cannot recover from this.
The system in question is an AMD Ryzen Threadripper 2950X, microcode
0x800820b, on an ASRock Fatal1ty X399 Professional Gaming, BIOS P3.30.
Change the code to handle (almost) arbitrary interruptions, as long
as they happen only once in a while and they do not take too long.
Specifically, also cover an interruption during the very first reads.
Here is some debug output on how the PIT behaves on my system during
a calibration with the patch applied.
The patch generating the output is at the bottom of this mail.
[ 0.000000] DMI: To Be Filled By O.E.M. To Be Filled By O.E.M./X399
Professional Gaming, BIOS P3.30 08/14/2018
[ 0.000000] tsc: pit_expect_msb: val=0xff cval=0xfe tsc=0x000000122fc5d195
delta=000000000000847b count=43
[ 0.000000] tsc: pit_expect_msb: val=0xfe cval=0xfd tsc=0x000000122fd12a95
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xfd cval=0xfc tsc=0x000000122fdcc62a
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xfc cval=0xfb tsc=0x000000122fe81ffc
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xfb cval=0xfa tsc=0x000000122ff378fc
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xfa cval=0xf9 tsc=0x000000122fff1491
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xf9 cval=0xf8 tsc=0x00000012300a6ea9
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xf8 cval=0xf7 tsc=0x000000123015c87b
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xf7 cval=0xf6 tsc=0x0000001230216410
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xf6 cval=0xf5 tsc=0x00000012302cbd10
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xf5 cval=0xf4 tsc=0x00000012303816e2
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xf4 cval=0xf3 tsc=0x000000123043b29a
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xf3 cval=0xf2 tsc=0x00000012304f0c8f
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xf2 cval=0xf1 tsc=0x00000012305a656c
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xf1 cval=0xf0 tsc=0x0000001230660101
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xf0 cval=0xef tsc=0x0000001230715b19
delta=000000000000831d count=41
[ 0.000000] tsc: pit_expect_msb: val=0xef cval=0xee tsc=0x00000012307cb4eb
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xee cval=0xed tsc=0x0000001230885080
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xed cval=0xec tsc=0x000000123093a980
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xec cval=0xeb tsc=0x00000012309f0398
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xeb cval=0xea tsc=0x0000001230aa9ee7
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xea cval=0xe9 tsc=0x0000001230b5f7e7
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe9 cval=0xe8 tsc=0x0000001230c151ff
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe8 cval=0xe7 tsc=0x0000001230cced94
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xe7 cval=0xe6 tsc=0x0000001230d8464e
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe6 cval=0xe5 tsc=0x0000001230e3a066
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe5 cval=0xe4 tsc=0x0000001230ef3bfb
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xe4 cval=0xe3 tsc=0x0000001230fa94d8
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe3 cval=0xe2 tsc=0x000000123105eef0
delta=000000000000831d count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe2 cval=0xe1 tsc=0x0000001231118a85
delta=000000000000831d count=42
[ 0.000000] tsc: pit_expect_msb: val=0xe1 cval=0xe0 tsc=0x00000012311ce457
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xe0 cval=0xdf tsc=0x0000001231283d57
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xdf cval=0xde tsc=0x000000123133d8ec
delta=0000000000008412 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xde cval=0xdd tsc=0x00000012313f3304
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xdd cval=0xdc tsc=0x00000012314a8cd6
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xdc cval=0xdb tsc=0x000000123156286b
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xdb cval=0xda tsc=0x000000123161816b
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xda cval=0xd9 tsc=0x00000012316cdb3d
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xd9 cval=0xd8 tsc=0x00000012317876d2
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xd8 cval=0xd7 tsc=0x000000123183d0ea
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xd7 cval=0xd6 tsc=0x00000012318f29a4
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xd6 cval=0xd5 tsc=0x00000012319ac539
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xd5 cval=0xd4 tsc=0x0000001231a61f51
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xd4 cval=0xd3 tsc=0x0000001231b17851
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xd3 cval=0xd2 tsc=0x0000001231bd13c3
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xd2 cval=0xd1 tsc=0x0000001231c86db8
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xd1 cval=0xd0 tsc=0x0000001231d40970
delta=0000000000008412 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xd0 cval=0xcf tsc=0x0000001231df6270
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xcf cval=0xce tsc=0x0000001231eabc42
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xce cval=0xcd tsc=0x0000001231f657d7
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xcd cval=0xcc tsc=0x000000123201b0d7
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xcc cval=0xcb tsc=0x00000012320d0aa9
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xcb cval=0xca tsc=0x000000123218a63e
delta=000000000000831d count=42
[ 0.000000] tsc: pit_expect_msb: val=0xca cval=0xc9 tsc=0x0000001232240056
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc9 cval=0xc8 tsc=0x00000012322f5910
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc8 cval=0xc7 tsc=0x00000012323af4a5
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xc7 cval=0xc6 tsc=0x0000001232464ebd
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc6 cval=0xc5 tsc=0x000000123251a88f
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc5 cval=0xc4 tsc=0x00000012325d4424
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xc4 cval=0xc3 tsc=0x0000001232689d47
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc3 cval=0xc2 tsc=0x000000123273f73c
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc2 cval=0xc1 tsc=0x00000012327f92ae
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xc1 cval=0xc0 tsc=0x00000012328aeca3
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xc0 cval=0xbf tsc=0x00000012329645c6
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xbf cval=0xbe tsc=0x0000001232a1e15b
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xbe cval=0xbd tsc=0x0000001232ad3b2d
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xbd cval=0xba tsc=0x0000001232b7ce35
delta=000000000019e745 count=38
[ 0.000000] tsc: pit_expect_msb: val=0xbc cval=0xba tsc=0x0000001232d1b692
delta=0000001232d1e9d7 count=0
[ 0.000000] tsc: pit_expect_msb: val=0xbb cval=0xba tsc=0x0000001232d23572
delta=0000001232d26de9 count=0
[ 0.000000] tsc: pit_expect_msb: val=0xba cval=0xb9 tsc=0x0000001232daf0cc
delta=0000000000008363 count=32
[ 0.000000] tsc: pit_expect_msb: val=0xb9 cval=0xb8 tsc=0x0000001232e64ae4
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xb8 cval=0xb7 tsc=0x0000001232f1e679
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xb7 cval=0xb6 tsc=0x0000001232fd3f79
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xb6 cval=0xb5 tsc=0x000000123308994b
delta=000000000000831d count=41
[ 0.000000] tsc: pit_expect_msb: val=0xb5 cval=0xb4 tsc=0x00000012331434e0
delta=000000000000831d count=42
[ 0.000000] tsc: pit_expect_msb: val=0xb4 cval=0xb3 tsc=0x00000012331f8ef8
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xb3 cval=0xb2 tsc=0x00000012332ae7b2
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xb2 cval=0xb1 tsc=0x000000123336836a
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xb1 cval=0xb0 tsc=0x000000123341dd5f
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xb0 cval=0xaf tsc=0x00000012334d3731
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xaf cval=0xae tsc=0x000000123358d2e9
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xae cval=0xad tsc=0x0000001233642be9
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xad cval=0xac tsc=0x00000012336f85bb
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xac cval=0xab tsc=0x00000012337b2150
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xab cval=0xaa tsc=0x0000001233867a50
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xaa cval=0xa9 tsc=0x000000123391d468
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa9 cval=0xa8 tsc=0x00000012339d6fb7
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xa8 cval=0xa7 tsc=0x0000001233a8c8b7
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa7 cval=0xa6 tsc=0x0000001233b422cf
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa6 cval=0xa5 tsc=0x0000001233bfbe64
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0xa5 cval=0xa4 tsc=0x0000001233cb171e
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa4 cval=0xa3 tsc=0x0000001233d67136
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa3 cval=0xa2 tsc=0x0000001233e20ccb
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0xa2 cval=0xa1 tsc=0x0000001233ed669d
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa1 cval=0xa0 tsc=0x0000001233f8bf9d
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0xa0 cval=0x9f tsc=0x0000001234045b55
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x9f cval=0x9e tsc=0x00000012340fb527
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x9e cval=0x9d tsc=0x00000012341b50bc
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x9d cval=0x9c tsc=0x000000123426aad4
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x9c cval=0x9b tsc=0x00000012343203d4
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x9b cval=0x9a tsc=0x00000012343d9f23
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x9a cval=0x99 tsc=0x000000123448f93b
delta=000000000000831d count=41
[ 0.000000] tsc: pit_expect_msb: val=0x99 cval=0x98 tsc=0x0000001234545353
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x98 cval=0x97 tsc=0x00000012345feea2
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x97 cval=0x96 tsc=0x00000012346b47a2
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x96 cval=0x95 tsc=0x000000123476a1ba
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x95 cval=0x94 tsc=0x0000001234823d4f
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x94 cval=0x93 tsc=0x00000012348d9609
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x93 cval=0x92 tsc=0x000000123498f021
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x92 cval=0x91 tsc=0x0000001234a48bb6
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x91 cval=0x90 tsc=0x0000001234afe493
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x90 cval=0x8f tsc=0x0000001234bb3e88
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x8f cval=0x8e tsc=0x0000001234c6da40
delta=0000000000008412 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x8e cval=0x8d tsc=0x0000001234d23340
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x8d cval=0x8c tsc=0x0000001234dd8d12
delta=0000000000008340 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x8c cval=0x8b tsc=0x0000001234e928a7
delta=000000000000831d count=42
[ 0.000000] tsc: pit_expect_msb: val=0x8b cval=0x8a tsc=0x0000001234f482bf
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x8a cval=0x89 tsc=0x0000001234ffdb79
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x89 cval=0x88 tsc=0x00000012350b770e
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x88 cval=0x87 tsc=0x000000123516d126
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x87 cval=0x86 tsc=0x0000001235222af8
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x86 cval=0x85 tsc=0x00000012352dc68d
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x85 cval=0x84 tsc=0x0000001235391f8d
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x84 cval=0x83 tsc=0x000000123544795f
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x83 cval=0x82 tsc=0x00000012355014f4
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x82 cval=0x81 tsc=0x00000012355b6f0c
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x81 cval=0x80 tsc=0x000000123566c80c
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x80 cval=0x7f tsc=0x000000123572637e
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x7f cval=0x7e tsc=0x00000012357dbd73
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x7e cval=0x7d tsc=0x0000001235891696
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x7d cval=0x7c tsc=0x000000123594b22b
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x7c cval=0x7b tsc=0x0000001235a00bfd
delta=0000000000008412 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x7b cval=0x7a tsc=0x0000001235ab64fd
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x7a cval=0x79 tsc=0x0000001235b70092
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x79 cval=0x78 tsc=0x0000001235c25a64
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x78 cval=0x77 tsc=0x0000001235cdb364
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x77 cval=0x76 tsc=0x0000001235d94ef9
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x76 cval=0x75 tsc=0x0000001235e4a8cb
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x75 cval=0x74 tsc=0x0000001235f002e3
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x74 cval=0x73 tsc=0x0000001235fb9e78
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x73 cval=0x72 tsc=0x000000123606f732
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x72 cval=0x71 tsc=0x000000123612514a
delta=000000000000831d count=41
[ 0.000000] tsc: pit_expect_msb: val=0x71 cval=0x70 tsc=0x00000012361decdf
delta=000000000000831d count=42
[ 0.000000] tsc: pit_expect_msb: val=0x70 cval=0x6f tsc=0x00000012362946f7
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x6f cval=0x6d tsc=0x0000001236444a56
delta=000000000017c488 count=11
[ 0.000000] tsc: pit_expect_msb: val=0x6e cval=0x6d tsc=0x000000123644ea4c
delta=0000001236452ce1 count=0
[ 0.000000] tsc: pit_expect_msb: val=0x6d cval=0x6c tsc=0x00000012364b9eaa
delta=0000000000008458 count=24
[ 0.000000] tsc: pit_expect_msb: val=0x6c cval=0x6b tsc=0x000000123656f87c
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x6b cval=0x6a tsc=0x0000001236629411
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x6a cval=0x69 tsc=0x00000012366dee29
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x69 cval=0x68 tsc=0x00000012367946e3
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x68 cval=0x67 tsc=0x000000123684e278
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x67 cval=0x66 tsc=0x0000001236903c90
delta=000000000000831d count=41
[ 0.000000] tsc: pit_expect_msb: val=0x66 cval=0x65 tsc=0x00000012369b9662
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x65 cval=0x64 tsc=0x0000001236a731f7
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x64 cval=0x63 tsc=0x0000001236b28af7
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x63 cval=0x62 tsc=0x0000001236bde50f
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x62 cval=0x61 tsc=0x0000001236c98081
delta=0000000000008363 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x61 cval=0x60 tsc=0x0000001236d4da99
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x60 cval=0x5f tsc=0x0000001236e03399
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x5f cval=0x5e tsc=0x0000001236ebcf2e
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x5e cval=0x5d tsc=0x0000001236f72900
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x5d cval=0x5c tsc=0x0000001237028200
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x5c cval=0x5b tsc=0x00000012370e1d95
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x5b cval=0x5a tsc=0x0000001237197767
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x5a cval=0x59 tsc=0x000000123724d067
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x59 cval=0x58 tsc=0x0000001237306bfc
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x58 cval=0x57 tsc=0x00000012373bc5ce
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x57 cval=0x56 tsc=0x0000001237471ece
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x56 cval=0x55 tsc=0x000000123752ba63
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x55 cval=0x54 tsc=0x00000012375e147b
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x54 cval=0x53 tsc=0x0000001237696e4d
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x53 cval=0x52 tsc=0x00000012377509e2
delta=0000000000008435 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x52 cval=0x51 tsc=0x0000001237806305
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x51 cval=0x50 tsc=0x00000012378bbcb4
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x50 cval=0x4f tsc=0x000000123797586c
delta=000000000000831d count=42
[ 0.000000] tsc: pit_expect_msb: val=0x4f cval=0x4e tsc=0x0000001237a2b284
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x4e cval=0x4d tsc=0x0000001237ae0b3e
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x4d cval=0x4c tsc=0x0000001237b9a6d3
delta=0000000000008458 count=42
[ 0.000000] tsc: pit_expect_msb: val=0x4c cval=0x4b tsc=0x0000001237c500eb
delta=0000000000008363 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x4b cval=0x4a tsc=0x0000001237d05abd
delta=0000000000008458 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x4a cval=0x49 tsc=0x0000001237dbf652
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x49 cval=0x48 tsc=0x0000001237e74f52
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x48 cval=0x47 tsc=0x0000001237f2a96a
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x47 cval=0x46 tsc=0x0000001237fe44b9
delta=000000000000847b count=42
[ 0.000000] tsc: pit_expect_msb: val=0x46 cval=0x45 tsc=0x0000001238099db9
delta=0000000000008435 count=41
[ 0.000000] tsc: pit_expect_msb: val=0x45 cval=0x44 tsc=0x000000123814f7d1
delta=000000000000847b count=41
[ 0.000000] tsc: pit_expect_msb: val=0x44 cval=0x43 tsc=0x0000001238209366
delta=000000000000847b count=42
[ 0.000000] tsc: Fast TSC calibration using PIT
[ 0.000000] tsc: Detected 3493.693 MHz processor
...
[ 2.343483] tsc: Refined TSC clocksource calibration: 3493.436 MHz
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index aced427371f7..1678e7c77abf 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -500,6 +500,8 @@ static inline int pit_expect_msb(unsigned char val, u64
*tscp, unsigned long *de
* We require _some_ success, but the quality control
* will be based on the error terms on the TSC values.
*/
+inb(0x42);
+pr_info("%s: val=0x%02x cval=0x%02x tsc=0x%016llx delta=%016lx count=%d\n",
__func__, val, inb(0x42), tsc, *deltap, count);
return count > 0 && pit_verify_msb(val - 1);
}
