Switching to automatic bigsmp causes a misleading error message, that more
then 8 cpus are detected, and user needs to select either X86_GENERICARCH
or X86_BIGSMP to handle.
Reason is we switched to bigsmp to avoid IP race when new cpu is comming
up. [bigsmp is nothing but using physical flat mode that can work for 1 ..
255 cpus] [default is X86_PC, that uses logical flat mode up to 8 CPUs
max] Current x86_64 code uses bigsmp as default when hotplug is enabled.
It would be preferable to make bigsmp as default, and work the dependencies
of other related code like SMP_SUSPEND, and some related to memory hotplug
code for i386.
Current logical flat mode doesnt use shortcuts that cause the race by using
the send_IPI_mask() instead of shortcuts when HOTPLUG_CPU is enabled.
In the meantime this patch is the path of lease resistance.
We will switch to bigsmp default sometime soon, when we get to work it again.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@suspend2.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
6cf272acd5