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authorRusty Russell <rusty@rustcorp.com.au>2007-07-27 05:42:52 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-29 04:54:33 +0200
commit6c8dca5d53f95009d4fff00195bf38f277dc4366 (patch)
tree60cc83cf949d6e598e6dc80dc668aebd42c65540 /drivers/lguest/interrupts_and_traps.c
parentFix lguest bzImage loading with CONFIG_RELOCATABLE=y (diff)
downloadlinux-6c8dca5d53f95009d4fff00195bf38f277dc4366.tar.xz
linux-6c8dca5d53f95009d4fff00195bf38f277dc4366.zip
Provide timespec to guests rather than jiffies clock.
A non-periodic clock_event_device and the "jiffies" clock don't mix well: tick_handle_periodic() can go into an infinite loop. Currently lguest guests use the jiffies clock when the TSC is unusable. Instead, make the Host write the current time into the lguest page on every interrupt. This doesn't cost much but is more precise and at least as accurate as the jiffies clock. It also gets rid of the GET_WALLCLOCK hypercall. Also, delay setting sched_clock until our clock is set up, otherwise the early printk timestamps can go backwards (not harmful, just ugly). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/lguest/interrupts_and_traps.c')
-rw-r--r--drivers/lguest/interrupts_and_traps.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index bd0091bf79ec..49787e964a0d 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -175,6 +175,13 @@ void maybe_do_interrupt(struct lguest *lg)
* the stack as well: virtual interrupts never do. */
set_guest_interrupt(lg, idt->a, idt->b, 0);
}
+
+ /* Every time we deliver an interrupt, we update the timestamp in the
+ * Guest's lguest_data struct. It would be better for the Guest if we
+ * did this more often, but it can actually be quite slow: doing it
+ * here is a compromise which means at least it gets updated every
+ * timer interrupt. */
+ write_timestamp(lg);
}
/*H:220 Now we've got the routines to deliver interrupts, delivering traps