o Kexec on panic functionality allocates memory for saving cpu registers
in case of system crash event. Address of this allocated memory needs to
be exported to user space, which is used by kexec-tools.
o Previously, a single /sys/kernel/crash_notes entry was being exported as
memory allocated was a single continuous array. Now memory allocation being
dyanmic and per cpu based, address of per cpu buffer is exported through
"/sys/devices/system/cpu/cpuX/crash_notes"
Signed-off-by: Vivek Goyal <[email protected]>
---
diff -puN drivers/base/cpu.c~kdump-export-crash-notes-through-sysfs drivers/base/cpu.c
--- linux-2.6.15-rc1-16M-dynamic/drivers/base/cpu.c~kdump-export-crash-notes-through-sysfs 2005-11-17 08:47:10.000000000 -0800
+++ linux-2.6.15-rc1-16M-dynamic-root/drivers/base/cpu.c 2005-11-17 08:49:33.000000000 -0800
@@ -83,6 +83,33 @@ static inline void register_cpu_control(
}
#endif /* CONFIG_HOTPLUG_CPU */
+#ifdef CONFIG_KEXEC
+#include <linux/kexec.h>
+
+static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
+{
+ struct cpu *cpu = container_of(dev, struct cpu, sysdev);
+ ssize_t rc;
+ unsigned long long addr;
+ int cpunum;
+
+ cpunum = cpu->sysdev.id;
+
+ /*
+ * Might be reading other cpu's data based on which cpu read thread
+ * has been scheduled. But cpu data (memory) is allocated once during
+ * boot up and this data does not change there after. Hence this
+ * operation should be safe. No locking required.
+ */
+ get_cpu();
+ addr = __pa(per_cpu_ptr(crash_notes, cpunum));
+ rc = sprintf(buf, "%Lx\n", addr);
+ put_cpu();
+ return rc;
+}
+static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
+#endif
+
/*
* register_cpu - Setup a driverfs device for a CPU.
* @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
@@ -108,6 +135,11 @@ int __devinit register_cpu(struct cpu *c
register_cpu_control(cpu);
if (!error)
cpu_sys_devices[num] = &cpu->sysdev;
+
+#ifdef CONFIG_KEXEC
+ if (!error)
+ error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
+#endif
return error;
}
diff -puN kernel/ksysfs.c~kdump-export-crash-notes-through-sysfs kernel/ksysfs.c
--- linux-2.6.15-rc1-16M-dynamic/kernel/ksysfs.c~kdump-export-crash-notes-through-sysfs 2005-11-17 08:47:10.000000000 -0800
+++ linux-2.6.15-rc1-16M-dynamic-root/kernel/ksysfs.c 2005-11-17 08:47:10.000000000 -0800
@@ -30,16 +30,6 @@ static ssize_t hotplug_seqnum_show(struc
KERNEL_ATTR_RO(hotplug_seqnum);
#endif
-#ifdef CONFIG_KEXEC
-#include <asm/kexec.h>
-
-static ssize_t crash_notes_show(struct subsystem *subsys, char *page)
-{
- return sprintf(page, "%p\n", (void *)crash_notes);
-}
-KERNEL_ATTR_RO(crash_notes);
-#endif
-
decl_subsys(kernel, NULL, NULL);
EXPORT_SYMBOL_GPL(kernel_subsys);
@@ -47,9 +37,6 @@ static struct attribute * kernel_attrs[]
#ifdef CONFIG_HOTPLUG
&hotplug_seqnum_attr.attr,
#endif
-#ifdef CONFIG_KEXEC
- &crash_notes_attr.attr,
-#endif
NULL
};
_
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
