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-rw-r--r--include/uapi/linux/ublk_cmd.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 5b71c19d3b9c..a7078b798791 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -408,6 +408,13 @@ struct ublk_shmem_buf_reg {
/* Disable automatic partition scanning when device is started */
#define UBLK_F_NO_AUTO_PART_SCAN (1ULL << 18)
+/*
+ * Enable shared memory zero copy. When enabled, the server can register
+ * shared memory buffers via UBLK_U_CMD_REG_BUF. If a block request's
+ * pages match a registered buffer, UBLK_IO_F_SHMEM_ZC is set and addr
+ * encodes the buffer index + offset instead of a userspace buffer address.
+ */
+#define UBLK_F_SHMEM_ZC (1ULL << 19)
/* device state */
#define UBLK_S_DEV_DEAD 0