[sdi] Add support for SDI images

Add support (disabled by default) for booting .sdi images as used by
Windows XP Embedded.

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

src/arch/i386/image/sdi.c

@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <realmode.h>
+#include <sdi.h>
+#include <ipxe/image.h>
+#include <ipxe/features.h>
+
+/** @file
+ *
+ * System Deployment Image (SDI)
+ *
+ * Based on the MSDN article "RAM boot using SDI in Windows XP
+ * Embedded with Service Pack 1", available at the time of writing
+ * from:
+ *
+ *   http://msdn.microsoft.com/en-us/library/ms838543.aspx
+ */
+
+FEATURE ( FEATURE_IMAGE, "SDI", DHCP_EB_FEATURE_SDI, 1 );
+
+/**
+ * Parse SDI image header
+ *
+ * @v image		SDI file
+ * @v sdi		SDI header to fill in
+ * @ret rc		Return status code
+ */
+static int sdi_parse_header ( struct image *image, struct sdi_header *sdi ) {
+
+	/* Sanity check */
+	if ( image->len < sizeof ( *sdi ) ) {
+		DBGC ( image, "SDI %p too short for SDI header\n", image );
+		return -ENOEXEC;
+	}
+
+	/* Read in header */
+	copy_from_user ( sdi, image->data, 0, sizeof ( *sdi ) );
+
+	/* Check signature */
+	if ( sdi->magic != SDI_MAGIC ) {
+		DBGC ( image, "SDI %p is not an SDI image\n", image );
+		return -ENOEXEC;
+	}
+
+	return 0;
+}
+
+/**
+ * Execute SDI image
+ *
+ * @v image		SDI file
+ * @ret rc		Return status code
+ */
+static int sdi_exec ( struct image *image ) {
+	struct sdi_header sdi;
+	uint32_t sdiptr;
+	int rc;
+
+	/* Parse image header */
+	if ( ( rc = sdi_parse_header ( image, &sdi ) ) != 0 )
+		return rc;
+
+	/* Check that image is bootable */
+	if ( sdi.boot_size == 0 ) {
+		DBGC ( image, "SDI %p is not bootable\n", image );
+		return -ENOTTY;
+	}
+	DBGC ( image, "SDI %p image at %08lx+%08zx\n",
+	       image, user_to_phys ( image->data, 0 ), image->len );
+	DBGC ( image, "SDI %p boot code at %08lx+%llx\n", image,
+	       user_to_phys ( image->data, sdi.boot_offset ), sdi.boot_size );
+
+	/* Copy boot code */
+	memcpy_user ( real_to_user ( SDI_BOOT_SEG, SDI_BOOT_OFF ), 0,
+		      image->data, sdi.boot_offset, sdi.boot_size );
+
+	/* Jump to boot code */
+	sdiptr = ( user_to_phys ( image->data, 0 ) | SDI_WTF );
+	__asm__ __volatile__ ( REAL_CODE ( "ljmp %0, %1\n\t" )
+			       : : "i" ( SDI_BOOT_SEG ),
+				   "i" ( SDI_BOOT_OFF ),
+				   "d" ( sdiptr ) );
+
+	/* There is no way for the image to return, since we provide
+	 * no return address.
+	 */
+	assert ( 0 );
+
+	return -ECANCELED; /* -EIMPOSSIBLE */
+}
+
+/**
+ * Probe SDI image
+ *
+ * @v image		SDI file
+ * @ret rc		Return status code
+ */
+static int sdi_probe ( struct image *image ) {
+	struct sdi_header sdi;
+	int rc;
+
+	/* Parse image */
+	if ( ( rc = sdi_parse_header ( image, &sdi ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
+/** SDI image type */
+struct image_type sdi_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "SDI",
+	.probe = sdi_probe,
+	.exec = sdi_exec,
+};

src/arch/i386/include/sdi.h

@@ -0,0 +1,39 @@
+#ifndef _SDI_H
+#define _SDI_H
+
+/** @file
+ *
+ * System Deployment Image (SDI)
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** SDI image header */
+struct sdi_header {
+	/** Signature */
+	uint32_t magic;
+	/** Version (as an ASCII string) */
+	uint32_t version;
+	/** Reserved */
+	uint8_t reserved[8];
+	/** Boot code offset */
+	uint64_t boot_offset;
+	/** Boot code size */
+	uint64_t boot_size;
+} __attribute__ (( packed ));
+
+/** SDI image signature */
+#define SDI_MAGIC \
+	( ( '$' << 0 ) | ( 'S' << 8 ) | ( 'D' << 16 ) | ( 'I' << 24 ) )
+
+/** SDI boot segment */
+#define SDI_BOOT_SEG 0x0000
+
+/** SDI boot offset */
+#define SDI_BOOT_OFF 0x7c00
+
+/** Constant to binary-OR with physical address of SDI image */
+#define SDI_WTF 0x41
+
+#endif /* _SDI_H */

src/arch/x86/include/bits/errfile.h

@@ -31,6 +31,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_com32          ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00080000 )
 #define ERRFILE_comboot_resolv ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00090000 )
 #define ERRFILE_comboot_call   ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x000a0000 )
+#define ERRFILE_sdi	       ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x000b0000 )
 
 #define ERRFILE_undi		 ( ERRFILE_ARCH | ERRFILE_NET | 0x00000000 )
 #define ERRFILE_undiload	 ( ERRFILE_ARCH | ERRFILE_NET | 0x00010000 )

src/config/config.c

@@ -181,6 +181,9 @@ REQUIRE_OBJECT ( comboot_resolv );
 #ifdef IMAGE_EFI
 REQUIRE_OBJECT ( efi_image );
 #endif
+#ifdef IMAGE_SDI
+REQUIRE_OBJECT ( sdi );
+#endif
 
 /*
  * Drag in all requested commands

src/config/general.h

@@ -100,6 +100,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 //#define	IMAGE_BZIMAGE		/* Linux bzImage image support */
 //#define	IMAGE_COMBOOT		/* SYSLINUX COMBOOT image support */
 //#define	IMAGE_EFI		/* EFI image support */
+//#define	IMAGE_SDI		/* SDI image support */
 
 /*
  * Command-line commands to include

src/include/ipxe/features.h

@@ -53,6 +53,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define DHCP_EB_FEATURE_FCOE		0x25 /**< FCoE protocol */
 #define DHCP_EB_FEATURE_VLAN		0x26 /**< VLAN support */
 #define DHCP_EB_FEATURE_MENU		0x27 /**< Menu support */
+#define DHCP_EB_FEATURE_SDI		0x28 /**< SDI image support */
 
 /** @} */