[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, 21 insertions, 1 deletions

diff --git a/src/include/ipxe/acpi.h b/src/include/ipxe/acpi.h
index eabbec390..282b6d92d 100644
--- a/src/include/ipxe/acpi.h
+++ b/src/include/ipxe/acpi.h
@@ -10,6 +10,7 @@
 FILE_LICENCE ( GPL2_OR_LATER );
 
 #include <stdint.h>
+#include <ipxe/interface.h>
 
 /**
  * An ACPI description header
@@ -19,7 +20,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
  */
 struct acpi_description_header {
 	/** ACPI signature (4 ASCII characters) */
-	char signature[4];
+	uint32_t signature;
 	/** Length of table, in bytes, including header */
 	uint32_t length;
 	/** ACPI Specification minor version number */
@@ -38,6 +39,25 @@ struct acpi_description_header {
 	uint32_t asl_compiler_revision;
 } __attribute__ (( packed ));
 
+/**
+ * Build ACPI signature
+ *
+ * @v a			First character of ACPI signature
+ * @v b			Second character of ACPI signature
+ * @v c			Third character of ACPI signature
+ * @v d			Fourth character of ACPI signature
+ * @ret signature	ACPI signature
+ */
+#define ACPI_SIGNATURE( a, b, c, d ) \
+	( ( (a) << 0 ) | ( (b) << 8 ) | ( (c) << 16 ) | ( (d) << 24 ) )
+
+extern int acpi_describe ( struct interface *interface,
+			   struct acpi_description_header *acpi, size_t len );
+#define acpi_describe_TYPE( object_type )				\
+	typeof ( int ( object_type,					\
+		       struct acpi_description_header *acpi,		\
+		       size_t len ) )
+
 extern void acpi_fix_checksum ( struct acpi_description_header *acpi );
 
 #endif /* _IPXE_ACPI_H */