Andrew Cooper
2013-Dec-02 15:34 UTC
[Patch v2] xen/x86: Be more power-efficient when waiting forever
The effect is unchanged, but the processor will be spending most of its time
in the C1 or C1E power state rather than C0.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>
CC: George Dunlap <george.dunlap@eu.citrix.com>
---
Changes in v2:
* Only change do_early_page_fault(). Leave the EFI dead code till 4.5
This was discovered while I was playing about in the early_page_fault()
handler with the IBM box which was corruption the Xen code section.
There is one final for(;;); loop, but is in common code and immediately
following a call to panic(), so is actually dead code and will be cleaned up
in v2 of my "noreturn" series at the start of 4.5
George: I am requesting that this get a freeze exception, under the
qualification of #2 "An awesome release", given no function change
threatening
---
xen/arch/x86/traps.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index d8b3eac..8c355e5 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1448,7 +1448,8 @@ void __init do_early_page_fault(struct cpu_user_regs
*regs)
printk("Stack dump: ");
while ( ((long)stk & ((PAGE_SIZE - 1) & ~(BYTES_PER_LONG - 1)))
!= 0 )
printk("%p ", _p(*stk++));
- for ( ; ; ) ;
+ for ( ; ; )
+ halt();
}
}
--
1.7.10.4