Added some code to call real mode pxe bios functions, based on Axel's bios_ia32/bios.S

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19619 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/boot/platform/pxe_ia32/Jamfile

@@ -42,6 +42,7 @@ local bios_ia32_edid_src =
 KernelMergeObject boot_platform_pxe_ia32.o :
 	pxe_stage2.S
 	smp_trampoline.S
+	pxe_bios.S
 	devices.cpp
 	network.cpp
 	pxe_undi.cpp

src/system/boot/platform/pxe_ia32/pxe_bios.S

@@ -0,0 +1,108 @@
+/*
+** Copyright 2004, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+** Copyright 2006, Marcus Overhagen, marcus@overhagen.de. All rights reserved.
+** Distributed under the terms of the Haiku License.
+*/
+
+
+/** This file contains code to call PXE BIOS functions out of a protected
+ *	mode environment. It doesn't use the virtual86 mode - it switches
+ *	to real mode, make the BIOS call, and switch back to protected
+ *	mode again. It's meant to be used in a single-threaded boot loader,
+ *	not in a multi-tasking operating system.
+ *	It relies on the real mode segment descriptors found in pxe_stage1.S,
+ *	and uses support functions from ../bios_ia32/bios.S
+ */
+
+#define FUNCTION(x) .globl x ; x ## :
+
+#define REAL_MODE_STACK	0x9000
+	// the location of the stack in real mode
+
+#define SAVED_ESP		0x10000
+#define SAVED_CR3		0x10004
+#define SAVED_EAX		0x10008
+#define SAVED_ES		0x1000c
+#define SAVED_FLAGS		0x10010
+	// we're overwriting the start of our boot loader to hold some
+	// temporary values - the first 1024 bytes of it are used at
+	// startup only, and we avoid some linking issues this way
+
+
+.text
+.code32
+
+
+/** void call_pxe_bios(...)
+ *	Does a call to the PXE BIOS functions in real mode.
+ */
+
+FUNCTION(call_pxe_bios)
+	pushal
+	pushfl
+
+	// make sure the correct IDT is in place
+	lidt 	idt_descriptor
+
+	// get the interrupt vector and patch the instruction at the target address
+	movl	40(%esp), %eax
+
+	// Fills registers from the passed in structure
+	// Since switch_to_real_mode() clobbers %eax, we have to handle
+	// it specially here (by temporarily storing it to an arbitrary
+	// memory location, SAVED_EAX)
+	movl	44(%esp), %ebp
+
+	movl	(%ebp), %eax
+	movl	%eax, SAVED_EAX
+	movl	4(%ebp), %ebx
+	movl	8(%ebp), %ecx
+	movl	12(%ebp), %edx
+	movl	16(%ebp), %esi
+	movl	20(%ebp), %edi
+	movw	24(%ebp), %ax
+	movw	%ax, SAVED_ES
+
+	call	switch_to_real_mode
+
+	.code16
+
+	// restore %eax and %es from saved location
+	movl	(SAVED_EAX - 0x10000), %eax
+	movw	(SAVED_ES - 0x10000), %es
+
+	// call the PXE hook
+
+
+
+	// we're interested in the flags state as well
+	pushf
+
+	// save %eax from the call
+	movl	%eax, (SAVED_EAX - 0x10000)
+
+	// save flags from the call
+	pop		%ax
+	movw	%ax, (SAVED_FLAGS - 0x10000)
+
+	// back to protected mode
+	call	switch_to_protected_mode
+	.code32
+
+	// store the register state into the structure that has been passed in
+	movl	44(%esp), %eax
+
+	movl	%ebx, 4(%eax)
+	movl	%ecx, 8(%eax)
+	movl	%edx, 12(%eax)
+	movl	%esi, 16(%eax)
+	movl	%edi, 20(%eax)
+	movl	SAVED_EAX, %ecx		// special handling for %eax and flags
+	movl	%ecx, (%eax)
+	movw	SAVED_FLAGS, %cx
+	movw	%cx, 26(%eax)
+
+	popfl
+	popal
+
+	ret