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a266d9f125
A workaround for AMD CPU family 11h erratum 311 might cause that the P-state Status Register shows a "current P-state" which is larger than the "current P-state limit" in P-state Current Limit Register. For the wrong P-state value there is no ACPI _PSS object defined and powernow-k8/cpufreq can't determine the proper CPU frequency for that state. As a consequence this can cause a panic during boot (potentially with all recent kernel versions -- at least I have reproduced it with various 2.6.27 kernels and with the current .28 series), as an example: powernow-k8: Found 1 AMD Turion(tm)X2 Ultra DualCore Mobile ZM-82 processors (2 \ ) powernow-k8: 0 : pstate 0 (2200 MHz) powernow-k8: 1 : pstate 1 (1100 MHz) powernow-k8: 2 : pstate 2 (600 MHz) BUG: unable to handle kernel paging request at ffff88086e7528b8 IP: [<ffffffff80486361>] cpufreq_stats_update+0x4a/0x5f PGD 202063 PUD 0 Oops: 0002 [#1] SMP last sysfs file: CPU 1 Modules linked in: Pid: 1, comm: swapper Not tainted 2.6.28-rc3-dirty #16 RIP: 0010:[<ffffffff80486361>] [<ffffffff80486361>] cpufreq_stats_update+0x4a/0\ f Synaptics claims to have extended capabilities, but I'm not able to read them.<6\ 6 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88006e7528c0 RDX: 00000000ffffffff RSI: ffff88006e54af00 RDI: ffffffff808f056c RBP: 00000000fffee697 R08: 0000000000000003 R09: ffff88006e73f080 R10: 0000000000000001 R11: 00000000002191c0 R12: ffff88006fb83c10 R13: 00000000ffffffff R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88006fb50740(0000) knlGS:0000000000000000 Unable to initialize Synaptics hardware. CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: ffff88086e7528b8 CR3: 0000000000201000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper (pid: 1, threadinfo ffff88006fb82000, task ffff88006fb816d0) Stack: ffff88006e74da50 0000000000000000 ffff88006e54af00 ffffffff804863c7 ffff88006e74da50 0000000000000000 00000000ffffffff 0000000000000000 ffff88006fb83c10 ffffffff8024b46c ffffffff808f0560 ffff88006fb83c10 Call Trace: [<ffffffff804863c7>] ? cpufreq_stat_notifier_trans+0x51/0x83 [<ffffffff8024b46c>] ? notifier_call_chain+0x29/0x4c [<ffffffff8024b561>] ? __srcu_notifier_call_chain+0x46/0x61 [<ffffffff8048496d>] ? cpufreq_notify_transition+0x93/0xa9 [<ffffffff8021ab8d>] ? powernowk8_target+0x1e8/0x5f3 [<ffffffff80486687>] ? cpufreq_governor_performance+0x1b/0x20 [<ffffffff80484886>] ? __cpufreq_governor+0x71/0xa8 [<ffffffff80484b21>] ? __cpufreq_set_policy+0x101/0x13e [<ffffffff80485bcd>] ? cpufreq_add_dev+0x3f0/0x4cd [<ffffffff8048577a>] ? handle_update+0x0/0x8 [<ffffffff803c2062>] ? sysdev_driver_register+0xb6/0x10d [<ffffffff8056592c>] ? powernowk8_init+0x0/0x7e [<ffffffff8048604c>] ? cpufreq_register_driver+0x8f/0x140 [<ffffffff80209056>] ? _stext+0x56/0x14f [<ffffffff802c2234>] ? proc_register+0x122/0x17d [<ffffffff802c23a0>] ? create_proc_entry+0x73/0x8a [<ffffffff8025c259>] ? register_irq_proc+0x92/0xaa [<ffffffff8025c2c8>] ? init_irq_proc+0x57/0x69 [<ffffffff807fc85f>] ? kernel_init+0x116/0x169 [<ffffffff8020cc79>] ? child_rip+0xa/0x11 [<ffffffff807fc749>] ? kernel_init+0x0/0x169 [<ffffffff8020cc6f>] ? child_rip+0x0/0x11 Code: 05 c5 83 36 00 48 c7 c2 48 5d 86 80 48 8b 04 d8 48 8b 40 08 48 8b 34 02 48\ RIP [<ffffffff80486361>] cpufreq_stats_update+0x4a/0x5f RSP <ffff88006fb83b20> CR2: ffff88086e7528b8 ---[ end trace 0678bac75e67a2f7 ]--- Kernel panic - not syncing: Attempted to kill init! In short, aftereffect of the wrong P-state is that cpufreq_stats_update() uses "-1" as index for some array in cpufreq_stats_update (unsigned int cpu) { ... if (stat->time_in_state) stat->time_in_state[stat->last_index] = cputime64_add(stat->time_in_state[stat->last_index], cputime_sub(cur_time, stat->last_time)); ... } Fortunately, the wrong P-state value is returned only if the core is in P-state 0. This fix solves the problem by detecting the out-of-range P-state, ignoring it, and using "0" instead. Cc: Mark Langsdorf <mark.langsdorf@amd.com> Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com> Signed-off-by: Dave Jones <davej@redhat.com> |
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