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authorSebastian Tanase <sebastian.tanase@openwide.fr>2014-07-25 11:56:29 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2014-08-06 17:53:07 +0200
commita8bfac37085c3372366d722f131a7e18d664ee4d (patch)
tree51cd30abe502c20f1334220a6766a3319219f0a6
parent1ad9580bd730f195a59136d11fdc431f90f266aa (diff)
downloadqemu-arm-a8bfac37085c3372366d722f131a7e18d664ee4d.tar.gz
icount: Add align option to icount
The align option is used for activating the align algorithm in order to synchronise the host clock and the guest clock. Signed-off-by: Sebastian Tanase <sebastian.tanase@openwide.fr> Tested-by: Camille Bégué <camille.begue@openwide.fr> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--cpus.c19
-rw-r--r--include/qemu-common.h1
-rw-r--r--qemu-options.hx15
-rw-r--r--vl.c4
4 files changed, 30 insertions, 9 deletions
diff --git a/cpus.c b/cpus.c
index 8291044203..7e09538799 100644
--- a/cpus.c
+++ b/cpus.c
@@ -476,25 +476,30 @@ static const VMStateDescription vmstate_timers = {
void configure_icount(QemuOpts *opts, Error **errp)
{
const char *option;
+ char *rem_str = NULL;
seqlock_init(&timers_state.vm_clock_seqlock, NULL);
vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
option = qemu_opt_get(opts, "shift");
if (!option) {
+ if (qemu_opt_get(opts, "align") != NULL) {
+ error_setg(errp, "Please specify shift option when using align");
+ }
return;
}
- /* When using -icount shift, the shift option will be
- misinterpreted as a boolean */
- if (strcmp(option, "on") == 0 || strcmp(option, "off") == 0) {
- error_setg(errp, "The shift option must be a number or auto");
- }
-
+ icount_align_option = qemu_opt_get_bool(opts, "align", false);
icount_warp_timer = timer_new_ns(QEMU_CLOCK_REALTIME,
icount_warp_rt, NULL);
if (strcmp(option, "auto") != 0) {
- icount_time_shift = strtol(option, NULL, 0);
+ errno = 0;
+ icount_time_shift = strtol(option, &rem_str, 0);
+ if (errno != 0 || *rem_str != '\0' || !strlen(option)) {
+ error_setg(errp, "icount: Invalid shift value");
+ }
use_icount = 1;
return;
+ } else if (icount_align_option) {
+ error_setg(errp, "shift=auto and align=on are incompatible");
}
use_icount = 2;
diff --git a/include/qemu-common.h b/include/qemu-common.h
index 04b0769c47..5d10ac27a1 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -108,6 +108,7 @@ static inline char *realpath(const char *path, char *resolved_path)
/* icount */
void configure_icount(QemuOpts *opts, Error **errp);
extern int use_icount;
+extern int icount_align_option;
#include "qemu/osdep.h"
#include "qemu/bswap.h"
diff --git a/qemu-options.hx b/qemu-options.hx
index 5a1b001881..96516c1e23 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3011,9 +3011,9 @@ re-inject them.
ETEXI
DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
- "-icount [shift=N|auto]\n" \
+ "-icount [shift=N|auto][,align=on|off]\n" \
" enable virtual instruction counter with 2^N clock ticks per\n" \
- " instruction\n", QEMU_ARCH_ALL)
+ " instruction and enable aligning the host and virtual clocks\n", QEMU_ARCH_ALL)
STEXI
@item -icount [shift=@var{N}|auto]
@findex -icount
@@ -3026,6 +3026,17 @@ Note that while this option can give deterministic behavior, it does not
provide cycle accurate emulation. Modern CPUs contain superscalar out of
order cores with complex cache hierarchies. The number of instructions
executed often has little or no correlation with actual performance.
+
+@option{align=on} will activate the delay algorithm which will try to
+to synchronise the host clock and the virtual clock. The goal is to
+have a guest running at the real frequency imposed by the shift option.
+Whenever the guest clock is behind the host clock and if
+@option{align=on} is specified then we print a messsage to the user
+to inform about the delay.
+Currently this option does not work when @option{shift} is @code{auto}.
+Note: The sync algorithm will work for those shift values for which
+the guest clock runs ahead of the host clock. Typically this happens
+when the shift value is high (how high depends on the host machine).
ETEXI
DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
diff --git a/vl.c b/vl.c
index f2621a50db..a8029d59d7 100644
--- a/vl.c
+++ b/vl.c
@@ -183,6 +183,7 @@ uint8_t *boot_splash_filedata;
size_t boot_splash_filedata_size;
uint8_t qemu_extra_params_fw[2];
+int icount_align_option;
typedef struct FWBootEntry FWBootEntry;
struct FWBootEntry {
@@ -546,6 +547,9 @@ static QemuOptsList qemu_icount_opts = {
{
.name = "shift",
.type = QEMU_OPT_STRING,
+ }, {
+ .name = "align",
+ .type = QEMU_OPT_BOOL,
},
{ /* end of list */ }
},