Due to commit:2103f6cba61a8b8bea3fc1b63661d830a2125e76, there is
a hotplug checking in machine_kexec_prepare(), but it will lead
a failure when loading the crash-kernel in some cases.
Kexec utility can load the crash kernel by two ways:
1. kexec -l kernel-image --append=command-line-options --initrd=initrd-image
2. kexec -p kernel-image --append=command-line-options --initrd=initrd-image
In case #1, it's ok to do the hotplug checking things, for it will cut off
cpus in _cpu_down() later when command "kexec -e" be sended, function
_cpu_down()
needs the support of cpu hotplug.
In case #2, it is no need to do the checking, because we actually do not
shut the cpus down, but just keep them invoking cpu_relax(), the whole routing
has no business with cpu cutting off. That means, even if the CONFIG_HOTPLUG_CPU
was not selected, it can also load and reboot the crash-kernel successfully if
we use "kexec -p ..." and then a crash came to trigger the kexec.
Prior to this patch, if the first kernel is not support the CPU hotplug, we can
not
use kexec utility.
Signed-off-by: Hu Keping <hukep...@huawei.com>
---
arch/arm/kernel/machine_kexec.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 8cf0996..1e5620f 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -41,12 +41,20 @@ int machine_kexec_prepare(struct kimage *image)
int i, err;
/*
- * Validate that if the current HW supports SMP, then the SW supports
- * and implements CPU hotplug for the current HW. If not, we won't be
- * able to kexec reliably, so fail the prepare operation.
+ * When it is a * crash * triggered the kexec, we do not really shut the
+ * cpus down but just let them keep invoking cpu_relax(), so there is
no need
+ * to do the hotplug checking things.
*/
- if (num_possible_cpus() > 1 && !platform_can_cpu_hotplug())
- return -EINVAL;
+ if (image->type != KEXEC_TYPE_CRASH)
+ {
+ /*
+ * Validate that if the current HW supports SMP, then the SW
supports
+ * and implements CPU hotplug for the current HW. If not, we
won't be
+ * able to kexec reliably, so fail the prepare operation.
+ */
+ if (num_possible_cpus() > 1 && !platform_can_cpu_hotplug())
+ return -EINVAL;
+ }
/*
* No segment at default ATAGs address. try to locate
--
1.8.5.5
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