Handle multi-sector reads by splitting them into subcommands.

src/drivers/ata/aoedev.c

 	struct aoe_device *aoedev
 		= container_of ( ata, struct aoe_device, ata );
 
-	return aoe_issue ( &aoedev->aoe, command );
+	return aoe_issue_split ( &aoedev->aoe, command );
 }
 
 /**

src/include/gpxe/aoe.h

 extern void aoe_open ( struct aoe_session *aoe );
 extern void aoe_close ( struct aoe_session *aoe );
 extern int aoe_issue ( struct aoe_session *aoe, struct ata_command *command );
+extern int aoe_issue_split ( struct aoe_session *aoe,
+			     struct ata_command *command );
 
 /** An AoE device */
 struct aoe_device {

src/include/gpxe/ata.h

 /** Master ("device 0") flag in the ATA device register */
 #define ATA_DEV_MASTER 0x00
 
+/** Mask of non-LBA portion of device register */
+#define ATA_DEV_MASK 0xf0
+
 /** "Read sectors" command */
 #define ATA_CMD_READ 0x20
 

src/net/aoe.c

 	aoecmd->cmd_stat = command->cb.cmd_stat;
 	aoecmd->lba.u64 = cpu_to_le64 ( command->cb.lba.native );
 	if ( ! command->cb.lba48 )
-		aoecmd->lba.bytes[3] |= command->cb.device;
+		aoecmd->lba.bytes[3] |= ( command->cb.device & ATA_DEV_MASK );
 
 	/* Fill data payload */
 	copy_from_user ( pkb_put ( pkb, command->data_out_len ),
  * Issue ATA command via an open AoE session
  *
  * @v aoe		AoE session
- * @v command		AoE command
+ * @v command		ATA command
  * @ret rc		Return status code
+ *
+ * The ATA command must fit within a single AoE frame (i.e. the sector
+ * count must not exceed AOE_MAX_COUNT).
  */
 int aoe_issue ( struct aoe_session *aoe, struct ata_command *command ) {
 	aoe->command = command;
 
 	return ( ( aoe->status & AOE_STATUS_ERR_MASK ) ? -EIO : 0 );
 }
+
+/**
+ * Issue ATA command via an open AoE session
+ *
+ * @v aoe		AoE session
+ * @v command		ATA command
+ * @ret rc		Return status code
+ *
+ * The ATA command will be split into several smaller ATA commands,
+ * each with a sector count no larger than AOE_MAX_COUNT.
+ */
+int aoe_issue_split ( struct aoe_session *aoe, struct ata_command *command ) {
+	struct ata_command subcommand;
+	unsigned int offset;
+	unsigned int count;
+	unsigned int data_len;
+	unsigned int status = 0;
+	int rc = 0;
+
+	/* Split ATA command into AoE-sized subcommands */
+	for ( offset = 0; offset < command->cb.count.native; offset += count ){
+		memcpy ( &subcommand, command, sizeof ( subcommand ) );
+		count = ( command->cb.count.native - offset );
+		if ( count > AOE_MAX_COUNT )
+			count = AOE_MAX_COUNT;
+		data_len = count * ATA_SECTOR_SIZE;
+		if ( subcommand.data_in_len )
+			subcommand.data_in_len = data_len;
+		if ( subcommand.data_out_len )
+			subcommand.data_out_len = data_len;
+		aoe->command_offset = ( offset * ATA_SECTOR_SIZE );
+		subcommand.cb.lba.native += offset;
+		subcommand.cb.count.native = count;
+		if ( ( rc = aoe_issue ( aoe, &subcommand ) ) != 0 )
+			goto done;
+		status |= subcommand.cb.cmd_stat;
+	}
+	command->cb.cmd_stat = status;
+
+ done:
+	aoe->command_offset = 0;
+	return rc;
+}