From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Hannemann Date: Wed, 21 Jul 2010 07:25:54 +0000 Subject: [bisected] sh_cmt Division by zero in kernel. Message-Id: <4C46A102.6000805@arndnet.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org Hi, when booting recent genesis-2.6 head on an AP4EVB board a division by zero in kernel is reported: (Looks identical to: http://thread.gmane.org/gmane.linux.ports.sh.devel/8497) [ 0.000000] sh_cmt.10: using deprecated clock lookup [ 0.000000] sh_cmt.10: used for clock events [ 0.000000] sh_cmt.10: used for periodic clock events [ 0.000000] Division by zero in kernel. [ 0.000000] Backtrace: [ 0.000000] [] (dump_backtrace+0x0/0x110) from [] (dump_stack+0x18/0x1c) [ 0.000000] r6:c0298978 r5:cf80e600 r4:cf801460 r3:c02a37ac [ 0.000000] [] (dump_stack+0x0/0x1c) from [] (__div0+0x18/0x20) [ 0.000000] [] (__div0+0x0/0x20) from [ ](Ldiv0+0x8/0x10) [ 0.000000] [] (sh_cmt_probe+0x0/0x4e4) from [ ](early_platform_driver_probe+0x1c8/0x264) [ 0.000000] [] (early_platform_driver_probe+0x0/0x264) from[] (shmobile_late_time_init+0x24/0x2c) [ 0.000000] [] (shmobile_late_time_init+0x0/0x2c) from[] (start_kernel+0x208/0x2a8) [ 0.000000] [] (start_kernel+0x0/0x2a8) from [<40008034>](0x40008034) [ 0.000000] r5:c02bd1f0 r4:10c53c7d [ 0.000000] sh_cmt.10: used as clock source and as a result time is running too fast. For example sleep 60 on bash returns after a few seconds. Git bisect identified following commit as bad: commit f4d7c3565c1692c54d9152b52090fe73f0029e37 Author: Paul Mundt Date: Wed Jun 2 17:10:44 2010 +0900 clocksource: sh_cmt: compute mult and shift before registration Based on the sh_tmu change in 66f49121ffa41a19c59965b31b046d8368fec3c7 ("clocksource: sh_tmu: compute mult and shift before registration"). The same issues impact the sh_cmt driver, so we take the same approach here. Cc: stable@kernel.org Signed-off-by: Paul Mundt Best regards, Arnd