On 05/18/2017 10:19 AM, Matt Redfearn wrote: > Hi Hauke, > > I would guess something to do with the conversion of the CPU interrupt > controller to IPI domains by patchset > https://patchwork.linux-mips.org/project/linux-mips/list/?series=255&state=*, > new in 4.12, has broken your IPIs and a CPU is getting stuck waiting for > the other to respond. > > Note that Paul says the Lantiq part of patch > https://patchwork.linux-mips.org/patch/15837/ > (1eed40043579608e16509c43eeeb3a53a8a42378) has only been compile tested. > > Thanks, > > Matt > > > On 17/05/17 23:12, Hauke Mehrtens wrote: >> Hi, >> >> I just tried to boot Linux 4.12-rc1 on a Lantiq Xway xrx200 board and >> boot failed when I had CONFIG_MIPS_MT_SMP enabled. >> >> It works with SMP on 4.9 and I think I also tried 4.11-rcX, but I am not >> 100% sure. I will investigate this problem further on Friday. >> >> If someone has an idea what I should test, I will do it on Friday. >> >> Both boot logs are attached to this mail. Hi Matt and Paul, you are correct, this commit breaks booting of Lantiq boards when SMP is enabled on 4.12-rc1: https://patchwork.linux-mips.org/patch/15837/ When I revert this commit or when I add the boot option nosmp the system boots again. The problem is that the Lantiq IRQ controller gets registered first and it directly handles the MIPS native SW1/2 and HW0 - HW5 IRQs. It looks like this controller already registers IRQ 0 - 7 and the generic driver only gets the following IRQs starting later. root@LEDE:/# cat /proc/interrupts CPU0 7: 26253 MIPS 7 timer 8: 0 MIPS 0 IPI call 9: 0 MIPS 1 IPI resched 22: 130 icu 22 spi_rx 23: 10 icu 23 spi_tx 24: 0 icu 24 spi_err 112: 142 icu 112 asc_tx 113: 27 icu 113 asc_rx 114: 0 icu 114 asc_err ERR: 0 root@LEDE:/# I see two options to fix this problem. 1. Revert the removing of the SMP IRQ code from arch/mips/lantiq/irq.c and make the generic code "register" IRQ 8 and 9 for SMP. 2. Make the Lantiq IRQ code use the generic MIPS IRQ code and only handle the Lantiq IRQ controller ICU and not the MIPS IRQs. Which option should I choose, or is there something else? Hauke
