Hi all, I'm running 3.4.17-rt28 on my mpc5200 based system. The complete system works pretty good until I select the "Fully Preemptible Kernel" option in the kernel settings. In that case, if I generate a high uart write load (sending a lot of stuff via Bluetooth) I get the following kernel Oops: # ------------[ cut here ]------------ Kernel BUG at c03d1728 [verbose debug info unavailable] Oops: Exception in kernel mode, sig: 5 [#1] PREEMPT mpc5200-simple-platform Modules linked in: NIP: c03d1728 LR: c03d170c CTR: c01efc78 REGS: c716fd30 TRAP: 0700 Not tainted (3.4.17-rt28/STW-V3.00r0+) MSR: 00029032 <EE,ME,IR,DR,RI> CR: 88002022 XER: 00000000 TASK = c7125880[633] 'irq/129-mpc52xx' THREAD: c716e000 GPR00: 00000001 c716fde0 c7125880 00000000 c7125880 00000000 00000001 00000000 GPR08: c7125880 c7125880 c7125880 c7125881 88002022 fbfdffff 07fff000 00000004 GPR16: 00000024 00000000 000000c0 00000000 c0537e70 00000004 00000000 00000004 GPR24: c716ad5c c0537e8c c7a73000 00000000 c7bb2a00 c7125880 c78b9800 c0537e8c NIP [c03d1728] rt_spin_lock_slowlock+0x78/0x1e0 LR [c03d170c] rt_spin_lock_slowlock+0x5c/0x1e0 Call Trace: [c716fde0] [c03d170c] rt_spin_lock_slowlock+0x5c/0x1e0 (unreliable) [c716fe40] [c01efcd4] uart_write+0x5c/0x114 [c716fe70] [c028f3f4] hci_uart_tx_wakeup+0xe0/0x1fc [c716fea0] [c01d3398] tty_wakeup+0x78/0xac [c716feb0] [c01ee9e0] uart_write_wakeup+0x24/0x34 [c716fec0] [c01f1c38] mpc52xx_psc_handle_irq+0x3f8/0x4b0 [c716ff20] [c01f13e4] mpc52xx_uart_int+0x38/0x60 [c716ff30] [c005f660] irq_forced_thread_fn+0x38/0x9c [c716ff50] [c005f42c] irq_thread+0x13c/0x1c0 [c716ff90] [c00391d4] kthread+0x8c/0x90 [c716fff0] [c000dd4c] kernel_thread+0x4c/0x68 Instruction dump: 7fe3fb78 7fa4eb78 38a00000 38c00001 4bc86591 2f830000 409e0134 801f0018 5400003c 7fa00278 7c000034 5400d97e <0f000000> 3bdd0418 3b810008 7fc3f378 If I switch the preemption modelt o "Preemptible Kernel (Basic RT)" everything works fine. Hope someone already had the same or similar problem and can help me solving it. Maybe a update to 3.4.27-rt39 helps? Thanks a lot Florian Belser -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html