Index: sbin/nvmecontrol/firmware.c
===================================================================
--- sbin/nvmecontrol/firmware.c
+++ sbin/nvmecontrol/firmware.c
@@ -155,21 +155,29 @@
 }
 
 static void
-update_firmware(int fd, uint8_t *payload, int32_t payload_size)
+update_firmware(int fd, uint8_t *payload, int32_t payload_size, uint8_t fwug)
 {
 	struct nvme_pt_command	pt;
+	uint64_t                max_xfer_size;
 	int32_t			off, resid, size;
 	void			*chunk;
 
 	off = 0;
 	resid = payload_size;
 
-	if ((chunk = aligned_alloc(PAGE_SIZE, NVME_MAX_XFER_SIZE)) == NULL)
-		errx(1, "unable to malloc %d bytes", NVME_MAX_XFER_SIZE);
+	if (fwug != 0 && fwug != 0xFF)
+		max_xfer_size = ((uint64_t)fwug << 12);
+	else if (ioctl(fd, NVME_GET_MAX_XFER_SIZE, &max_xfer_size) < 0)
+ 		err(1, "query max transfer size failed");
+ 	if (max_xfer_size > NVME_MAX_XFER_SIZE)
+ 		max_xfer_size = NVME_MAX_XFER_SIZE;
 
+	if ((chunk = aligned_alloc(PAGE_SIZE, max_xfer_size)) == NULL)
+		errx(1, "unable to malloc %zd bytes", (size_t)max_xfer_size);
+
 	while (resid > 0) {
-		size = (resid >= NVME_MAX_XFER_SIZE) ?
-		    NVME_MAX_XFER_SIZE : resid;
+		size = (resid >= (int32_t)max_xfer_size) ?
+		    max_xfer_size : resid;
 		memcpy(chunk, payload + off, size);
 
 		memset(&pt, 0, sizeof(pt));
@@ -333,7 +341,7 @@
 	}
 
 	if (opt.fw_img != NULL) {
-		update_firmware(fd, buf, size);
+		update_firmware(fd, buf, size, cdata.fwug);
 		if (opt.activate)
 			activate_action = NVME_AA_REPLACE_ACTIVATE;
 		else
Index: sbin/nvmecontrol/identify_ext.c
===================================================================
--- sbin/nvmecontrol/identify_ext.c
+++ sbin/nvmecontrol/identify_ext.c
@@ -56,6 +56,7 @@
 	uint8_t ns_smart;
 	uint8_t sqes_max, sqes_min;
 	uint8_t cqes_max, cqes_min;
+	uint8_t fwug;
 
 	oncs = cdata->oncs;
 	compare = (oncs >> NVME_CTRLR_DATA_ONCS_COMPARE_SHIFT) &
@@ -79,6 +80,7 @@
 		NVME_CTRLR_DATA_FRMW_NUM_SLOTS_MASK;
 	fw_slot1_ro = (cdata->frmw >> NVME_CTRLR_DATA_FRMW_SLOT1_RO_SHIFT) &
 		NVME_CTRLR_DATA_FRMW_SLOT1_RO_MASK;
+	fwug = cdata->fwug;
 
 	ns_smart = (cdata->lpa >> NVME_CTRLR_DATA_LPA_NS_SMART_SHIFT) &
 		NVME_CTRLR_DATA_LPA_NS_SMART_MASK;
@@ -192,6 +194,13 @@
 		    uint128_to_str(to128(cdata->untncap.unvmcap),
 		    cbuf, sizeof(cbuf)));
 	}
+	printf("Firmware Update Granularity: %02x ", fwug);
+	if (fwug == 0)
+		printf("(Not Reported)\n");
+	else if (fwug == 0xFF)
+		printf("(No Granularity)\n");
+	else
+		printf("(%d bytes)\n", ((uint32_t)fwug << 12));
 	printf("Host Buffer Preferred Size:  %llu bytes\n",
 	    (long long unsigned)cdata->hmpre * 4096);
 	printf("Host Buffer Minimum Size:    %llu bytes\n",
Index: sys/dev/nvme/nvme.h
===================================================================
--- sys/dev/nvme/nvme.h
+++ sys/dev/nvme/nvme.h
@@ -41,6 +41,7 @@
 #define	NVME_PASSTHROUGH_CMD		_IOWR('n', 0, struct nvme_pt_command)
 #define	NVME_RESET_CONTROLLER		_IO('n', 1)
 #define	NVME_GET_NSID			_IOR('n', 2, struct nvme_get_nsid)
+#define NVME_GET_MAX_XFER_SIZE		_IOR('n', 3, uint64_t)
 
 #define	NVME_IO_TEST			_IOWR('n', 100, struct nvme_io_test)
 #define	NVME_BIO_TEST			_IOWR('n', 101, struct nvme_io_test)
Index: sys/dev/nvme/nvme_ctrlr.c
===================================================================
--- sys/dev/nvme/nvme_ctrlr.c
+++ sys/dev/nvme/nvme_ctrlr.c
@@ -1345,6 +1345,9 @@
 		gnsid->nsid = 0;
 		break;
 	}
+	case NVME_GET_MAX_XFER_SIZE:
+		*(uint64_t *)arg = ctrlr->max_xfer_size;
+		break;
 	default:
 		return (ENOTTY);
 	}