MFC 307845

    hyperv/ic: Rework framework/message version negotiation.

    Submitted by:   Hongjiang Zhang <honzhan microsoft com>
    Modified by:    sephe
    Sponsored by:   Microsoft
    Differential Revision:  https://reviews.freebsd.org/D8280

9 files changed, 207 insertions, 88 deletions

diff --git a/sys/dev/hyperv/utilities/hv_heartbeat.c b/sys/dev/hyperv/utilities/hv_heartbeat.c
index 3786714..8fc7a09 100644
--- a/sys/dev/hyperv/utilities/hv_heartbeat.c
+++ b/sys/dev/hyperv/utilities/hv_heartbeat.c
@@ -40,6 +40,14 @@ __FBSDID("$FreeBSD$");
 
 #include "vmbus_if.h"
 
+#define VMBUS_HEARTBEAT_FWVER_MAJOR	3
+#define VMBUS_HEARTBEAT_FWVER		\
+	VMBUS_IC_VERSION(VMBUS_HEARTBEAT_FWVER_MAJOR, 0)
+
+#define VMBUS_HEARTBEAT_MSGVER_MAJOR	3
+#define VMBUS_HEARTBEAT_MSGVER		\
+	VMBUS_IC_VERSION(VMBUS_HEARTBEAT_MSGVER_MAJOR, 0)
+
 static const struct vmbus_ic_desc vmbus_heartbeat_descs[] = {
 	{
 		.ic_guid = { .hv_guid = {
@@ -80,7 +88,8 @@ vmbus_heartbeat_cb(struct vmbus_channel *chan, void *xsc)
 	 */
 	switch (hdr->ic_type) {
 	case VMBUS_ICMSG_TYPE_NEGOTIATE:
-		error = vmbus_ic_negomsg(sc, data, &dlen);
+		error = vmbus_ic_negomsg(sc, data, &dlen,
+		    VMBUS_HEARTBEAT_FWVER, VMBUS_HEARTBEAT_MSGVER);
 		if (error)
 			return;
 		break;
diff --git a/sys/dev/hyperv/utilities/hv_kvp.c b/sys/dev/hyperv/utilities/hv_kvp.c
index 9d1abb4..593b422 100644
--- a/sys/dev/hyperv/utilities/hv_kvp.c
+++ b/sys/dev/hyperv/utilities/hv_kvp.c
@@ -61,7 +61,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/mutex.h>
 
 #include <dev/hyperv/include/hyperv.h>
+#include <dev/hyperv/include/vmbus.h>
 #include <dev/hyperv/utilities/hv_utilreg.h>
+#include <dev/hyperv/utilities/vmbus_icreg.h>
 
 #include "hv_util.h"
 #include "unicode.h"
@@ -74,6 +76,12 @@ __FBSDID("$FreeBSD$");
 #define KVP_ERROR	1
 #define kvp_hdr		hdr.kvp_hdr
 
+#define KVP_FWVER_MAJOR		3
+#define KVP_FWVER		VMBUS_IC_VERSION(KVP_FWVER_MAJOR, 0)
+
+#define KVP_MSGVER_MAJOR	4
+#define KVP_MSGVER		VMBUS_IC_VERSION(KVP_MSGVER_MAJOR, 0)
+
 /* hv_kvp debug control */
 static int hv_kvp_log = 0;
 
@@ -208,52 +216,10 @@ hv_kvp_transaction_init(hv_kvp_sc *sc, uint32_t rcv_len,
 	sc->host_msg_id = request_id;
 	sc->rcv_buf = rcv_buf;
 	sc->host_kvp_msg = (struct hv_kvp_msg *)&rcv_buf[
-		sizeof(struct hv_vmbus_pipe_hdr) +
-		sizeof(struct hv_vmbus_icmsg_hdr)];
+	    sizeof(struct hv_vmbus_pipe_hdr) +
+	    sizeof(struct hv_vmbus_icmsg_hdr)];
 }
 
-
-/*
- * hv_kvp - version neogtiation function
- */
-static void
-hv_kvp_negotiate_version(struct hv_vmbus_icmsg_hdr *icmsghdrp, uint8_t *buf)
-{
-	struct hv_vmbus_icmsg_negotiate *negop;
-	int icframe_vercnt;
-	int icmsg_vercnt;
-
-	icmsghdrp->icmsgsize = 0x10;
-
-	negop = (struct hv_vmbus_icmsg_negotiate *)&buf[
-		sizeof(struct hv_vmbus_pipe_hdr) +
-		sizeof(struct hv_vmbus_icmsg_hdr)];
-	icframe_vercnt = negop->icframe_vercnt;
-	icmsg_vercnt = negop->icmsg_vercnt;
-
-	/*
-	 * Select the framework version number we will support
-	 */
-	if ((icframe_vercnt >= 2) && (negop->icversion_data[1].major == 3)) {
-		icframe_vercnt = 3;
-		if (icmsg_vercnt > 2)
-			icmsg_vercnt = 4;
-		else
-			icmsg_vercnt = 3;
-	} else {
-		icframe_vercnt = 1;
-		icmsg_vercnt = 1;
-	}
-
-	negop->icframe_vercnt = 1;
-	negop->icmsg_vercnt = 1;
-	negop->icversion_data[0].major = icframe_vercnt;
-	negop->icversion_data[0].minor = 0;
-	negop->icversion_data[1].major = icmsg_vercnt;
-	negop->icversion_data[1].minor = 0;
-}
-
-
 /*
  * Convert ip related info in umsg from utf8 to utf16 and store in hmsg
  */
@@ -578,7 +544,8 @@ hv_kvp_respond_host(hv_kvp_sc *sc, int error)
 		error = HV_KVP_E_FAIL;
 
 	hv_icmsg_hdrp->status = error;
-	hv_icmsg_hdrp->icflags = HV_ICMSGHDRFLAG_TRANSACTION | HV_ICMSGHDRFLAG_RESPONSE;
+	hv_icmsg_hdrp->icflags = HV_ICMSGHDRFLAG_TRANSACTION |
+	    HV_ICMSGHDRFLAG_RESPONSE;
 
 	error = vmbus_chan_send(vmbus_get_channel(sc->dev),
 	    VMBUS_CHANPKT_TYPE_INBAND, 0, sc->rcv_buf, sc->host_msg_len,
@@ -622,8 +589,8 @@ hv_kvp_process_request(void *context, int pending)
 	uint32_t recvlen = 0;
 	uint64_t requestid;
 	struct hv_vmbus_icmsg_hdr *icmsghdrp;
-	int ret = 0;
-	hv_kvp_sc		*sc;
+	int ret = 0, error;
+	hv_kvp_sc *sc;
 
 	hv_kvp_log_info("%s: entering hv_kvp_process_request\n", __func__);
 
@@ -637,14 +604,15 @@ hv_kvp_process_request(void *context, int pending)
 	/* XXX check recvlen to make sure that it contains enough data */
 
 	while ((ret == 0) && (recvlen > 0)) {
-
 		icmsghdrp = (struct hv_vmbus_icmsg_hdr *)
-			&kvp_buf[sizeof(struct hv_vmbus_pipe_hdr)];
+		    &kvp_buf[sizeof(struct hv_vmbus_pipe_hdr)];
 
 		hv_kvp_transaction_init(sc, recvlen, requestid, kvp_buf);
 		if (icmsghdrp->icmsgtype == HV_ICMSGTYPE_NEGOTIATE) {
-			hv_kvp_negotiate_version(icmsghdrp, kvp_buf);
-			hv_kvp_respond_host(sc, ret);
+			error = vmbus_ic_negomsg(&sc->util_sc,
+			    kvp_buf, &recvlen, KVP_FWVER, KVP_MSGVER);
+			/* XXX handle vmbus_ic_negomsg failure. */
+			hv_kvp_respond_host(sc, error);
 
 			/*
 			 * It is ok to not acquire the mutex before setting
diff --git a/sys/dev/hyperv/utilities/hv_kvp.h b/sys/dev/hyperv/utilities/hv_kvp.h
index 6474e18..c391da0 100644
--- a/sys/dev/hyperv/utilities/hv_kvp.h
+++ b/sys/dev/hyperv/utilities/hv_kvp.h
@@ -28,7 +28,6 @@
 
 #ifndef _KVP_H
 #define _KVP_H
-
 /*
  * An implementation of HyperV key value pair (KVP) functionality for FreeBSD
  *
@@ -178,9 +177,9 @@ struct hv_kvp_ipaddr_value {
 }__attribute__((packed));
 
 struct hv_kvp_hdr {
-	uint8_t  operation;
-	uint8_t  pool;
-	uint16_t pad;
+	uint8_t                 operation;
+	uint8_t                 pool;
+	uint16_t                pad;
 } __attribute__((packed));
 
 struct hv_kvp_exchg_msg_value {
diff --git a/sys/dev/hyperv/utilities/hv_shutdown.c b/sys/dev/hyperv/utilities/hv_shutdown.c
index 4580093..e511b21 100644
--- a/sys/dev/hyperv/utilities/hv_shutdown.c
+++ b/sys/dev/hyperv/utilities/hv_shutdown.c
@@ -41,6 +41,14 @@ __FBSDID("$FreeBSD$");
 
 #include "vmbus_if.h"
 
+#define VMBUS_SHUTDOWN_FWVER_MAJOR	3
+#define VMBUS_SHUTDOWN_FWVER		\
+	VMBUS_IC_VERSION(VMBUS_SHUTDOWN_FWVER_MAJOR, 0)
+
+#define VMBUS_SHUTDOWN_MSGVER_MAJOR	3
+#define VMBUS_SHUTDOWN_MSGVER		\
+	VMBUS_IC_VERSION(VMBUS_SHUTDOWN_MSGVER_MAJOR, 0)
+
 static const struct vmbus_ic_desc vmbus_shutdown_descs[] = {
 	{
 		.ic_guid = { .hv_guid = {
@@ -82,7 +90,8 @@ vmbus_shutdown_cb(struct vmbus_channel *chan, void *xsc)
 	 */
 	switch (hdr->ic_type) {
 	case VMBUS_ICMSG_TYPE_NEGOTIATE:
-		error = vmbus_ic_negomsg(sc, data, &dlen);
+		error = vmbus_ic_negomsg(sc, data, &dlen,
+		    VMBUS_SHUTDOWN_FWVER, VMBUS_SHUTDOWN_MSGVER);
 		if (error)
 			return;
 		break;
diff --git a/sys/dev/hyperv/utilities/hv_timesync.c b/sys/dev/hyperv/utilities/hv_timesync.c
index 2d44026..5bd51b0 100644
--- a/sys/dev/hyperv/utilities/hv_timesync.c
+++ b/sys/dev/hyperv/utilities/hv_timesync.c
@@ -42,6 +42,14 @@ __FBSDID("$FreeBSD$");
 
 #include "vmbus_if.h"
 
+#define VMBUS_TIMESYNC_FWVER_MAJOR	3
+#define VMBUS_TIMESYNC_FWVER		\
+	VMBUS_IC_VERSION(VMBUS_TIMESYNC_FWVER_MAJOR, 0)
+
+#define VMBUS_TIMESYNC_MSGVER_MAJOR	3
+#define VMBUS_TIMESYNC_MSGVER		\
+	VMBUS_IC_VERSION(VMBUS_TIMESYNC_MSGVER_MAJOR, 0)
+
 static const struct vmbus_ic_desc vmbus_timesync_descs[] = {
 	{
 		.ic_guid = { .hv_guid = {
@@ -162,7 +170,8 @@ vmbus_timesync_cb(struct vmbus_channel *chan, void *xsc)
 	 */
 	switch (hdr->ic_type) {
 	case VMBUS_ICMSG_TYPE_NEGOTIATE:
-		error = vmbus_ic_negomsg(sc, data, &dlen);
+		error = vmbus_ic_negomsg(sc, data, &dlen,
+		    VMBUS_TIMESYNC_FWVER, VMBUS_TIMESYNC_MSGVER);
 		if (error)
 			return;
 		break;
diff --git a/sys/dev/hyperv/utilities/hv_util.c b/sys/dev/hyperv/utilities/hv_util.c
index 3fc16c9..20b8f84 100644
--- a/sys/dev/hyperv/utilities/hv_util.c
+++ b/sys/dev/hyperv/utilities/hv_util.c
@@ -37,6 +37,7 @@
 #include <sys/module.h>
 #include <sys/reboot.h>
 #include <sys/systm.h>
+#include <sys/sysctl.h>
 #include <sys/timetc.h>
 
 #include <dev/hyperv/include/hyperv.h>
@@ -53,52 +54,145 @@
 	__offsetof(struct vmbus_icmsg_negotiate, ic_ver[VMBUS_IC_VERCNT])
 CTASSERT(VMBUS_IC_NEGOSZ < VMBUS_IC_BRSIZE);
 
+static int	vmbus_ic_fwver_sysctl(SYSCTL_HANDLER_ARGS);
+static int	vmbus_ic_msgver_sysctl(SYSCTL_HANDLER_ARGS);
+
 int
-vmbus_ic_negomsg(struct hv_util_sc *sc, void *data, int *dlen0)
+vmbus_ic_negomsg(struct hv_util_sc *sc, void *data, int *dlen0,
+    uint32_t fw_ver, uint32_t msg_ver)
 {
 	struct vmbus_icmsg_negotiate *nego;
-	int cnt, major, dlen = *dlen0;
+	int i, cnt, dlen = *dlen0, error;
+	uint32_t sel_fw_ver, sel_msg_ver;
+	bool has_fw_ver, has_msg_ver;
 
 	/*
-	 * Preliminary message size verification
+	 * Preliminary message verification.
 	 */
 	if (dlen < sizeof(*nego)) {
 		device_printf(sc->ic_dev, "truncated ic negotiate, len %d\n",
 		    dlen);
-		return EINVAL;
+		return (EINVAL);
 	}
 	nego = data;
 
+	if (nego->ic_fwver_cnt == 0) {
+		device_printf(sc->ic_dev, "ic negotiate does not contain "
+		    "framework version %u\n", nego->ic_fwver_cnt);
+		return (EINVAL);
+	}
+	if (nego->ic_msgver_cnt == 0) {
+		device_printf(sc->ic_dev, "ic negotiate does not contain "
+		    "message version %u\n", nego->ic_msgver_cnt);
+		return (EINVAL);
+	}
+
 	cnt = nego->ic_fwver_cnt + nego->ic_msgver_cnt;
 	if (dlen < __offsetof(struct vmbus_icmsg_negotiate, ic_ver[cnt])) {
 		device_printf(sc->ic_dev, "ic negotiate does not contain "
 		    "versions %d\n", dlen);
-		return EINVAL;
+		return (EINVAL);
+	}
+
+	error = EOPNOTSUPP;
+
+	/*
+	 * Find the best match framework version.
+	 */
+	has_fw_ver = false;
+	for (i = 0; i < nego->ic_fwver_cnt; ++i) {
+		if (VMBUS_ICVER_LE(nego->ic_ver[i], fw_ver)) {
+			if (!has_fw_ver) {
+				sel_fw_ver = nego->ic_ver[i];
+				has_fw_ver = true;
+			} else if (VMBUS_ICVER_GT(nego->ic_ver[i],
+			    sel_fw_ver)) {
+				sel_fw_ver = nego->ic_ver[i];
+			}
+		}
+	}
+	if (!has_fw_ver) {
+		device_printf(sc->ic_dev, "failed to select framework "
+		    "version\n");
+		goto done;
+	}
+
+	/*
+	 * Fine the best match message version.
+	 */
+	has_msg_ver = false;
+	for (i = nego->ic_fwver_cnt;
+	    i < nego->ic_fwver_cnt + nego->ic_msgver_cnt; ++i) {
+		if (VMBUS_ICVER_LE(nego->ic_ver[i], msg_ver)) {
+			if (!has_msg_ver) {
+				sel_msg_ver = nego->ic_ver[i];
+				has_msg_ver = true;
+			} else if (VMBUS_ICVER_GT(nego->ic_ver[i],
+			    sel_msg_ver)) {
+				sel_msg_ver = nego->ic_ver[i];
+			}
+		}
+	}
+	if (!has_msg_ver) {
+		device_printf(sc->ic_dev, "failed to select message "
+		    "version\n");
+		goto done;
 	}
 
-	/* Select major version; XXX looks wrong. */
-	if (nego->ic_fwver_cnt >= 2 && VMBUS_ICVER_MAJOR(nego->ic_ver[1]) == 3)
-		major = 3;
-	else
-		major = 1;
+	error = 0;
+done:
+	if (bootverbose || !has_fw_ver || !has_msg_ver) {
+		if (has_fw_ver) {
+			device_printf(sc->ic_dev, "sel framework version: "
+			    "%u.%u\n",
+			    VMBUS_ICVER_MAJOR(sel_fw_ver),
+			    VMBUS_ICVER_MINOR(sel_fw_ver));
+		}
+		for (i = 0; i < nego->ic_fwver_cnt; i++) {
+			device_printf(sc->ic_dev, "supp framework version: "
+			    "%u.%u\n",
+			    VMBUS_ICVER_MAJOR(nego->ic_ver[i]),
+			    VMBUS_ICVER_MINOR(nego->ic_ver[i]));
+		}
+
+		if (has_msg_ver) {
+			device_printf(sc->ic_dev, "sel message version: "
+			    "%u.%u\n",
+			    VMBUS_ICVER_MAJOR(sel_msg_ver),
+			    VMBUS_ICVER_MINOR(sel_msg_ver));
+		}
+		for (i = nego->ic_fwver_cnt;
+		    i < nego->ic_fwver_cnt + nego->ic_msgver_cnt; i++) {
+			device_printf(sc->ic_dev, "supp message version: "
+			    "%u.%u\n",
+			    VMBUS_ICVER_MAJOR(nego->ic_ver[i]),
+			    VMBUS_ICVER_MINOR(nego->ic_ver[i]));
+		}
+	}
+	if (error)
+		return (error);
+
+	/* Record the selected versions. */
+	sc->ic_fwver = sel_fw_ver;
+	sc->ic_msgver = sel_msg_ver;
 
-	/* One framework version */
+	/* One framework version. */
 	nego->ic_fwver_cnt = 1;
-	nego->ic_ver[0] = VMBUS_IC_VERSION(major, 0);
+	nego->ic_ver[0] = sel_fw_ver;
 
-	/* One message version */
+	/* One message version. */
 	nego->ic_msgver_cnt = 1;
-	nego->ic_ver[1] = VMBUS_IC_VERSION(major, 0);
+	nego->ic_ver[1] = sel_msg_ver;
 
-	/* Update data size */
+	/* Update data size. */
 	nego->ic_hdr.ic_dsize = VMBUS_IC_NEGOSZ -
 	    sizeof(struct vmbus_icmsg_hdr);
 
-	/* Update total size, if necessary */
+	/* Update total size, if necessary. */
 	if (dlen < VMBUS_IC_NEGOSZ)
 		*dlen0 = VMBUS_IC_NEGOSZ;
 
-	return 0;
+	return (0);
 }
 
 int
@@ -124,6 +218,8 @@ hv_util_attach(device_t dev, vmbus_chan_callback_t cb)
 {
 	struct hv_util_sc *sc = device_get_softc(dev);
 	struct vmbus_channel *chan = vmbus_get_channel(dev);
+	struct sysctl_oid_list *child;
+	struct sysctl_ctx_list *ctx;
 	int error;
 
 	sc->ic_dev = dev;
@@ -146,9 +242,41 @@ hv_util_attach(device_t dev, vmbus_chan_callback_t cb)
 		free(sc->receive_buffer, M_DEVBUF);
 		return (error);
 	}
+
+	ctx = device_get_sysctl_ctx(dev);
+	child = SYSCTL_CHILDREN(device_get_sysctl_tree(dev));
+	SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "fw_version",
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, sc, 0,
+	    vmbus_ic_fwver_sysctl, "A", "framework version");
+	SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "msg_version",
+	    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, sc, 0,
+	    vmbus_ic_msgver_sysctl, "A", "message version");
+
 	return (0);
 }
 
+static int
+vmbus_ic_fwver_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	struct hv_util_sc *sc = arg1;
+	char verstr[16];
+
+	snprintf(verstr, sizeof(verstr), "%u.%u",
+	    VMBUS_ICVER_MAJOR(sc->ic_fwver), VMBUS_ICVER_MINOR(sc->ic_fwver));
+	return sysctl_handle_string(oidp, verstr, sizeof(verstr), req);
+}
+
+static int
+vmbus_ic_msgver_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	struct hv_util_sc *sc = arg1;
+	char verstr[16];
+
+	snprintf(verstr, sizeof(verstr), "%u.%u",
+	    VMBUS_ICVER_MAJOR(sc->ic_msgver), VMBUS_ICVER_MINOR(sc->ic_msgver));
+	return sysctl_handle_string(oidp, verstr, sizeof(verstr), req);
+}
+
 int
 hv_util_detach(device_t dev)
 {
diff --git a/sys/dev/hyperv/utilities/hv_util.h b/sys/dev/hyperv/utilities/hv_util.h
index 012cdee..7cf8d31 100644
--- a/sys/dev/hyperv/utilities/hv_util.h
+++ b/sys/dev/hyperv/utilities/hv_util.h
@@ -42,6 +42,8 @@ typedef struct hv_util_sc {
 	device_t		ic_dev;
 	uint8_t			*receive_buffer;
 	int			ic_buflen;
+	uint32_t		ic_fwver;	/* framework version */
+	uint32_t		ic_msgver;	/* message version */
 } hv_util_sc;
 
 struct vmbus_ic_desc {
@@ -54,6 +56,7 @@ struct vmbus_ic_desc {
 int		hv_util_attach(device_t dev, vmbus_chan_callback_t cb);
 int		hv_util_detach(device_t dev);
 int		vmbus_ic_probe(device_t dev, const struct vmbus_ic_desc descs[]);
-int		vmbus_ic_negomsg(struct hv_util_sc *, void *data, int *dlen);
+int		vmbus_ic_negomsg(struct hv_util_sc *sc, void *data, int *dlen,
+		    uint32_t fw_ver, uint32_t msg_ver);
 
 #endif
diff --git a/sys/dev/hyperv/utilities/hv_utilreg.h b/sys/dev/hyperv/utilities/hv_utilreg.h
index 124de41..9358776 100644
--- a/sys/dev/hyperv/utilities/hv_utilreg.h
+++ b/sys/dev/hyperv/utilities/hv_utilreg.h
@@ -76,16 +76,4 @@ typedef struct hv_vmbus_icmsg_negotiate {
 	hv_vmbus_ic_version	icversion_data[1]; /* any size array */
 } __packed hv_vmbus_icmsg_negotiate;
 
-typedef struct hv_vmbus_shutdown_msg_data {
-	uint32_t		reason_code;
-	uint32_t		timeout_seconds;
-	uint32_t 		flags;
-	uint8_t			display_message[2048];
-} __packed hv_vmbus_shutdown_msg_data;
-
-typedef struct hv_vmbus_heartbeat_msg_data {
-	uint64_t 		seq_num;
-	uint32_t 		reserved[8];
-} __packed hv_vmbus_heartbeat_msg_data;
-
 #endif	/* !_HV_UTILREG_H_ */
diff --git a/sys/dev/hyperv/utilities/vmbus_icreg.h b/sys/dev/hyperv/utilities/vmbus_icreg.h
index 683e2f8..3435962 100644
--- a/sys/dev/hyperv/utilities/vmbus_icreg.h
+++ b/sys/dev/hyperv/utilities/vmbus_icreg.h
@@ -42,6 +42,12 @@
 #define VMBUS_IC_VERSION(major, minor)	((major) | (((uint32_t)(minor)) << 16))
 #define VMBUS_ICVER_MAJOR(ver)		((ver) & 0xffff)
 #define VMBUS_ICVER_MINOR(ver)		(((ver) & 0xffff0000) >> 16)
+#define VMBUS_ICVER_SWAP(ver)		\
+	((VMBUS_ICVER_MAJOR((ver)) << 16) | VMBUS_ICVER_MINOR((ver)))
+#define VMBUS_ICVER_LE(v1, v2)		\
+	(VMBUS_ICVER_SWAP((v1)) <= VMBUS_ICVER_SWAP((v2)))
+#define VMBUS_ICVER_GT(v1, v2)		\
+	(VMBUS_ICVER_SWAP((v1)) > VMBUS_ICVER_SWAP((v2)))
 
 struct vmbus_pipe_hdr {
 	uint32_t		ph_flags;