Malta defconfig compiles with GIC on. Hence when compiling for SMP it causes the new IPI code to be activated. But on qemu malta there's no GIC causing a BUG_ON(!ipidomain) to be hit in mips_smp_ipi_init(). Since in that configuration one can only run a single core SMP (!), skip IPI initialisation if we detect that this is the case. It is a sensible behaviour to introduce and should keep such possible configuration to run rather than die hard unnecessarily. Signed-off-by: Qais Yousef <qsyousef@xxxxxxxxx> Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx> Cc: Guenter Roeck <linux@xxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx --- arch/mips/kernel/smp.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c index 37708d9..27cb638 100644 --- a/arch/mips/kernel/smp.c +++ b/arch/mips/kernel/smp.c @@ -243,6 +243,18 @@ static int __init mips_smp_ipi_init(void) struct irq_domain *ipidomain; struct device_node *node; + /* + * In some cases like qemu-malta, it is desired to try SMP with + * a single core. Qemu-malta has no GIC, so an attempt to set any IPIs + * would cause a BUG_ON() to be triggered since there's no ipidomain. + * + * Since for a single core system IPIs aren't required really, skip the + * initialisation which should generally keep any such configurations + * happy and only fail hard when trying to truely run SMP. + */ + if (cpumask_weight(cpu_possible_mask) == 1) + return 0; + node = of_irq_find_parent(of_root); ipidomain = irq_find_matching_host(node, DOMAIN_BUS_IPI); -- 2.7.3
