diff --git a/.gitignore b/.gitignore
index 4d41277..fb92f9b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
 build/
 *.bin
 *.elf
+
+.vscode/
diff --git a/source/vdev/sdcard.c b/source/vdev/sdcard.c
index fb0e6f4..64c331f 100644
--- a/source/vdev/sdcard.c
+++ b/source/vdev/sdcard.c
@@ -3,7 +3,13 @@
 #include "hw/sdmmc.h"
 #include "virt/manager.h"
 
-#define VIRTIO_BLK_F_RO	BIT(5)
+#define VIRTIO_BLK_F_SIZE_MAX	BIT(1)
+#define VIRTIO_BLK_F_SEG_MAX	BIT(2)
+#define VIRTIO_BLK_F_READONLY	BIT(5)
+#define VIRTIO_BLK_F_BLK_SIZE	BIT(6)
+
+#define VIRTIO_BLK_TYPE_IN	0
+#define VIRTIO_BLK_TYPE_OUT	1
 
 typedef struct {
 	u64 capacity;
@@ -37,8 +43,8 @@ typedef struct {
 } PACKED blk_config;
 
 typedef struct {
-	u32 resv;
 	u32 type;
+	u32 resv;
 	u64 sector_offset;
 } PACKED vblk_t;
 
@@ -50,7 +56,9 @@ static void sdmc_hard_reset(vdev_s *vdev) {
 		data[i] = 0;
 	sdmmc_sdcard_init();
 	sdmc_blk_config.capacity = sdmmc_sdcard_size();
-	sdmc_blk_config.blk_size = 512;
+	sdmc_blk_config.blk_size = 512u;
+	sdmc_blk_config.size_max = 512u * ((1u << 16) - 1); // limited by hardware
+	sdmc_blk_config.seg_max = 16u; // picked by a fair dice roll
 }
 
 static u8 sdmc_cfg_read(vdev_s *vdev, uint offset) {
@@ -59,39 +67,64 @@ static u8 sdmc_cfg_read(vdev_s *vdev, uint offset) {
 	return 0xFF;
 }
 
+static void sdmc_txrx(vqueue_s *vq, const vblk_t *blk, vjob_s *vj) {
+	int err = 0;
+	u32 type = blk->type, offset = blk->sector_offset;
+
+	while(vqueue_fetch_job_next(vq, vj) >= 0) {
+		vdesc_s desc;
+		vqueue_get_job_desc(vq, vj, &desc);
+
+		u8 *data = desc.data;
+		u32 len = desc.length;
+
+		if ((len % 512) == 0) {
+			u32 nsect = len / 512;
+
+			if (type == VIRTIO_BLK_TYPE_IN) {
+				// SD -> memory
+				err |= sdmmc_sdcard_readsectors(offset, nsect, data) ? 1 : 0;
+				vjob_add_written(vj, len);
+			} else if (type == VIRTIO_BLK_TYPE_OUT) {
+				// memory -> SD
+				err |= sdmmc_sdcard_writesectors(offset, nsect, data) ? 1 : 0;
+			} else {
+				__builtin_trap();
+				__builtin_unreachable();
+			}
+
+			data += len;
+			offset += nsect;
+		} else if ((len % 512) == 1) {
+			// assume single status byte
+			*data = err;
+		} else {
+			__builtin_trap();
+			__builtin_unreachable();
+		}
+	}
+}
+
 static void sdmc_process_vqueue(vdev_s *vdev, vqueue_s *vq) {
 	vjob_s vjob;
 
 	while(vqueue_fetch_job_new(vq, &vjob) >= 0) {
-		do {
-			u32 *data;
-			vdesc_s desc;
-			vqueue_get_job_desc(vq, &vjob, &desc);
-
-			if (desc.dir == HOST_TO_VDEV) {
-				const vblk_t *blk = (const vblk_t*)desc.data;
-				OBJ_SETPRIV(vq, (u32)blk->sector_offset);
-			} else {
-				u8 *data = desc.data;
-				if (desc.length < 512) {
-					*data = 0;
-				} else {
-					u32 sectors = desc.length >> 9;
-					sdmmc_sdcard_readsectors(OBJ_GETPRIV(vq, u32), sectors, data);
-					OBJ_SETPRIV(vq, OBJ_GETPRIV(vq, u32) + sectors);
-					vjob_add_written(&vjob, desc.length);
-				}
-			}
-		} while(vqueue_fetch_job_next(vq, &vjob) >= 0);
+		vblk_t vblk;
+		vdesc_s desc;
+		vqueue_get_job_desc(vq, &vjob, &desc);
+
+		vblk = *(volatile vblk_t*)(desc.data);
+
+		sdmc_txrx(vq, &vblk, &vjob);
+
 		vqueue_push_job(vq, &vjob);
+		vman_notify_host(vdev, VIRQ_VQUEUE);
 	}
-
-	vman_notify_host(vdev, VIRQ_VQUEUE);
 }
 
 DECLARE_VIRTDEV(
 	vdev_sdcard, NULL,
-	VDEV_T_BLOCK, VIRTIO_BLK_F_RO, 1,
+	VDEV_T_BLOCK, VIRTIO_BLK_F_SIZE_MAX | VIRTIO_BLK_F_SEG_MAX | VIRTIO_BLK_F_BLK_SIZE, 1,
 	sdmc_hard_reset,
 	sdmc_cfg_read, vdev_cfg_write_stub,
 	sdmc_process_vqueue