[block] Replace gPXE block-device API with an iPXE asynchronous interface

The block device interface used in gPXE predates the invention of even
the old gPXE data-transfer interface, let alone the current iPXE
generic asynchronous interface mechanism.  Bring this old code up to
date, with the following benefits:

 o  Block device commands can be cancelled by the requestor.  The INT 13
    layer uses this to provide a global timeout on all INT 13 calls,
    with the result that an unexpected passive failure mode (such as
    an iSCSI target ACKing the request but never sending a response)
    will lead to a timeout that gets reported back to the INT 13 user,
    rather than simply freezing the system.

 o  INT 13,00 (reset drive) is now able to reset the underlying block
    device.  INT 13 users, such as DOS, that use INT 13,00 as a method
    for error recovery now have a chance of recovering.

 o  All block device commands are tagged, with a numerical tag that
    will show up in debugging output and in packet captures; this will
    allow easier interpretation of bug reports that include both
    sources of information.

 o  The extremely ugly hacks used to generate the boot firmware tables
    have been eradicated and replaced with a generic acpi_describe()
    method (exploiting the ability of iPXE interfaces to pass through
    methods to an underlying interface).  The ACPI tables are now
    built in a shared data block within .bss16, rather than each
    requiring dedicated space in .data16.

 o  The architecture-independent concept of a SAN device has been
    exposed to the iPXE core through the sanboot API, which provides
    calls to hook, unhook, boot, and describe SAN devices.  This
    allows for much more flexible usage patterns (such as hooking an
    empty SAN device and then running an OS installer via TFTP).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 25 insertions, 46 deletions

diff --git a/src/include/ipxe/iscsi.h b/src/include/ipxe/iscsi.h
index a604e1e4f..e711459c9 100644
--- a/src/include/ipxe/iscsi.h
+++ b/src/include/ipxe/iscsi.h
@@ -90,6 +90,9 @@ struct iscsi_bhs_common {
 /** Final PDU of a sequence */
 #define ISCSI_FLAG_FINAL 0x80
 
+/** iSCSI tag magic marker */
+#define ISCSI_TAG_MAGIC 0x18ae0000
+
 /**
  * iSCSI basic header segment common request fields
  *
@@ -307,8 +310,10 @@ struct iscsi_bhs_scsi_response {
 	uint32_t maxcmdsn;
 	/** Expected data sequence number */
 	uint32_t expdatasn;
-	/** Reserved */
-	uint8_t reserved_b[8];
+	/** Bidirectional read residual count */
+	uint32_t bidi_residual_count;
+	/** Residual count */
+	uint32_t residual_count;
 };
 
 /** SCSI response opcode */
@@ -320,13 +325,11 @@ struct iscsi_bhs_scsi_response {
 /** SCSI target failure */
 #define ISCSI_RESPONSE_TARGET_FAILURE 0x01
 
-/** SCSI sense response code offset
- *
- * The SCSI response may contain unsolicited sense data in the data
- * segment.  If it does, this is the offset to the sense response code
- * byte, which is the only byte we care about.
- */
-#define ISCSI_SENSE_RESPONSE_CODE_OFFSET 2
+/** Data overflow occurred */
+#define ISCSI_RESPONSE_FLAG_OVERFLOW 0x20
+
+/** Data underflow occurred */
+#define ISCSI_RESPONSE_FLAG_UNDERFLOW 0x40
 
 /**
  * iSCSI data-in basic header segment
@@ -497,6 +500,10 @@ struct iscsi_session {
 	/** Reference counter */
 	struct refcnt refcnt;
 
+	/** SCSI command-issuing interface */
+	struct interface control;
+	/** SCSI command interface */
+	struct interface data;
 	/** Transport-layer socket */
 	struct interface socket;
 
@@ -506,10 +513,6 @@ struct iscsi_session {
 	unsigned int target_port;
 	/** Target IQN */
 	char *target_iqn;
-	/** Logical Unit Number (LUN) */
-	struct scsi_lun lun;
-	/** Target socket address (recorded only for iBFT) */
-	struct sockaddr target_sockaddr;
 
 	/** Session status
 	 *
@@ -517,12 +520,6 @@ struct iscsi_session {
 	 * constants.
 	 */
 	int status;
-	/** Retry count
-	 *
-	 * Number of times that the connection has been retried.
-	 * Reset upon a successful connection.
-	 */
-	int retry_count;
 
 	/** Initiator username (if any) */
 	char *initiator_username;
@@ -542,12 +539,6 @@ struct iscsi_session {
 	/** CHAP response (used for both initiator and target auth) */
 	struct chap_response chap;
 
-	/** Target session identifying handle
-	 *
-	 * This is assigned by the target when we first log in, and
-	 * must be reused on subsequent login attempts.
-	 */
-	uint16_t tsih;
 	/** Initiator task tag
 	 *
 	 * This is the tag of the current command.  It is incremented
@@ -560,15 +551,13 @@ struct iscsi_session {
 	 * response to an R2T.
 	 */
 	uint32_t ttt;
-	/**
-	 * Transfer offset
+	/** Transfer offset
 	 *
 	 * This is the offset for an in-progress sequence of data-out
 	 * PDUs in response to an R2T.
 	 */
 	uint32_t transfer_offset;
-	/**
-	 * Transfer length
+	/** Transfer length
 	 *
 	 * This is the length for an in-progress sequence of data-out
 	 * PDUs in response to an R2T.
@@ -609,18 +598,13 @@ struct iscsi_session {
 	/** Buffer for received data (not always used) */
 	void *rx_buffer;
 
-	/** Current SCSI command
-	 *
-	 * Set to NULL when command is complete.
-	 */
-	struct scsi_command *command;
-	/** Instant return code
-	 *
-	 * Set to a non-zero value if all requests should return
-	 * immediately.  This can be used to e.g. avoid retrying
-	 * logins that are doomed to fail authentication.
-	 */
-	int instant_rc;
+	/** Current SCSI command, if any */
+	struct scsi_cmd *command;
+
+	/** Target socket address (for boot firmware table) */
+	struct sockaddr target_sockaddr;
+	/** SCSI LUN (for boot firmware table) */
+	struct scsi_lun lun;
 };
 
 /** iSCSI session is currently in the security negotiation phase */
@@ -668,11 +652,6 @@ struct iscsi_session {
 /** Target authenticated itself correctly */
 #define ISCSI_STATUS_AUTH_REVERSE_OK 0x00040000
 
-/** Maximum number of retries at connecting */
-#define ISCSI_MAX_RETRIES 2
-
-extern int iscsi_attach ( struct scsi_device *scsi, const char *root_path );
-extern void iscsi_detach ( struct scsi_device *scsi );
 extern const char * iscsi_initiator_iqn ( void );
 
 #endif /* _IPXE_ISCSI_H */