CTB_DESC_SIZE
blob_size = 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE + CTB_G2H_BUFFER_SIZE;
cmds = blob + 2 * CTB_DESC_SIZE;
desc = blob + CTB_DESC_SIZE;
cmds = blob + 2 * CTB_DESC_SIZE + CTB_H2G_BUFFER_SIZE;