Date: Thu, 15 Apr 2010 10:33:47 +0200 (CEST) From: Andre Albsmeier <Andre.Albsmeier@siemens.com> To: FreeBSD-gnats-submit@FreeBSD.org Subject: i386/145718: [PATCH] fix freq calculation from MSR for CPUs with fractional multipliers Message-ID: <201004150833.o3F8XliI017683@curry.mchp.siemens.de> Resent-Message-ID: <201004150840.o3F8e18A033684@freefall.freebsd.org>
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>Number: 145718 >Category: i386 >Synopsis: [PATCH] fix freq calculation from MSR for CPUs with fractional multipliers >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-i386 >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Thu Apr 15 08:40:00 UTC 2010 >Closed-Date: >Last-Modified: >Originator: Andre Albsmeier >Release: FreeBSD 7.3-STABLE i386 >Organization: >Environment: System: FreeBSD 7.3-STABLE #6: Thu Apr 15 09:42:06 CEST 2010 using a Q9550 cpu >Description: When calculating the simple rate table in est_msr_info() we have to observe bit 6 (0x40) of the multiplier which denotes an additional 0.5 for the value. Examples: FID Multiplier -------------------- 0x06 6 0x07 7 0x08 8 0x46 6.5 0x47 7.5 0x48 8.5 >How-To-Repeat: Enable cpufreq on a cpu with a fractional multiplier (in my case a Q9550 which uses 8.5), set hw.est.msr_info=1, and watch dmesg spitting out insane low/high values for the bus clock. >Fix: --- est.c.ORI 2009-07-14 08:57:29.000000000 +0200 +++ est.c 2010-04-15 10:29:11.000000000 +0200 @@ -1207,11 +1207,15 @@ freq = tsc_freq / 1000000; id = msr >> 32; bus = freq / (id >> 8); + if( id & 0x4000 ) + bus = 2 * freq / ( (id >> 7 & 0x7e) + 1 ); device_printf(dev, "Guessed bus clock (high) of %d MHz\n", bus); if (!bus_speed_ok(bus)) { /* We may be running on the low frequency. */ id = msr >> 48; bus = freq / (id >> 8); + if( id & 0x4000 ) + bus = 2 * freq / ( (id >> 7 & 0x7e) + 1 ); device_printf(dev, "Guessed bus clock (low) of %d MHz\n", bus); if (!bus_speed_ok(bus)) return (EOPNOTSUPP); @@ -1219,6 +1223,8 @@ /* Calculate high frequency. */ id = msr >> 32; freq = ((id >> 8) & 0xff) * bus; + if( id & 0x4000 ) + freq =( (id >> 7 & 0x7e) + 1 ) * bus / 2; } /* Fill out a new freq table containing just the high and low freqs. */ @@ -1241,6 +1247,8 @@ /* Second, the low frequency. */ id = msr >> 48; freq = ((id >> 8) & 0xff) * bus; + if( id & 0x4000 ) + freq =( (id >> 7 & 0x7e) + 1 ) * bus / 2; volts = id & 0xff; if (volts != 0) { volts <<= 4; >Release-Note: >Audit-Trail: >Unformatted:
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