Index: sys/boot/efi/boot1/zfs_module.c
===================================================================
--- sys/boot/efi/boot1/zfs_module.c
+++ sys/boot/efi/boot1/zfs_module.c
@@ -45,22 +45,48 @@
 {
 	dev_info_t *devinfo;
 	off_t lba;
+	size_t size, reminder;
+	char *bouncebuf = NULL;
 	EFI_STATUS status;
 
 	devinfo = (dev_info_t *)priv;
 	lba = off / devinfo->dev->Media->BlockSize;
+	reminder = off % devinfo->dev->Media->BlockSize;
 
-	status = devinfo->dev->ReadBlocks(devinfo->dev,
-	    devinfo->dev->Media->MediaId, lba, bytes, buf);
-	if (status != EFI_SUCCESS) {
-		DPRINTF("vdev_read: failed dev: %p, id: %u, lba: %jd, size: %zu,"
-		    " status: %lu\n", devinfo->dev,
-		    devinfo->dev->Media->MediaId, (intmax_t)lba, bytes,
-		    EFI_ERROR_CODE(status));
-		return (-1);
+	/*
+	 * If we have reminder from off, we need to add reminder part.
+	 * Since buffer must be multiple of the BlockSize, round it all up.
+	 */
+	size = roundup2(bytes + reminder, devinfo->dev->Media->BlockSize);
+
+	if (reminder != 0 || size != bytes) {
+		bouncebuf = malloc(size);
+		if (bouncebuf == NULL) {
+			printf("vdev_read: out of memory\n");
+			return (-1);
+		}
+		status = devinfo->dev->ReadBlocks(devinfo->dev,
+		    devinfo->dev->Media->MediaId, lba, size, bouncebuf);
+		if (EFI_ERROR(status)) {
+			free(bouncebuf);
+			goto error;
+		}
+		memcpy(buf, bouncebuf+reminder, bytes);
+		free(bouncebuf);
+	} else {
+		status = devinfo->dev->ReadBlocks(devinfo->dev,
+		    devinfo->dev->Media->MediaId, lba, bytes, buf);
+		if (EFI_ERROR(status))
+			goto error;
 	}
 
 	return (0);
+error:
+	DPRINTF("vdev_read: failed dev: %p, id: %u, lba: %jd, size: %zu,"
+	    " status: %lu\n", devinfo->dev,
+	    devinfo->dev->Media->MediaId, (intmax_t)lba, bytes,
+	    EFI_ERROR_CODE(status));
+	return (-1);
 }
 
 static EFI_STATUS