mirror of https://github.com/torvalds/linux.git
ab84ba647f
On a platform using the "Multiprocessor Wakeup Structure"[1] to startup
secondary CPUs the control processor needs to memremap() the physical
address of the MP Wakeup Structure mailbox to the variable
acpi_mp_wake_mailbox, which holds the virtual address of mailbox.
To wake up the AP the control processor writes the APIC ID of AP, the
wakeup vector and the ACPI_MP_WAKE_COMMAND_WAKEUP command into the mailbox.
Current implementation doesn't consider the case which restricts boot time
CPU bringup to 1 with the kernel parameter "maxcpus=1" and brings other
CPUs online later from user space as it sets acpi_mp_wake_mailbox to
read-only after init. So when the first AP is tried to brought online
after init, the attempt to update the variable results in a kernel panic.
The memremap() call that initializes the variable cannot be moved into
acpi_parse_mp_wake() because memremap() is not functional at that point in
the boot process. Also as the APs might never be brought up, keep the
memremap() call in acpi_wakeup_cpu() so that the operation only takes place
when needed.
Fixes:
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|---|---|---|
| .. | ||
| Makefile | ||
| apei.c | ||
| boot.c | ||
| cppc.c | ||
| cstate.c | ||
| madt_playdead.S | ||
| madt_wakeup.c | ||
| sleep.c | ||
| sleep.h | ||
| wakeup_32.S | ||
| wakeup_64.S | ||