[coreboot] VSA and vm86/x86emu

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Tue Feb 19 01:51:48 CET 2008


On 18.02.2008 23:55, Marc Jones wrote:
> Carl-Daniel Hailfinger wrote:
>> it seems that executing VSA requires vm86 to be useful. Since we
>> unconditionally execute the VSA, we should unconditionally require vm86
>> support (PCI_OPTION_ROM_RUN_VM86) via Kconfig for Geode targets. Not
>> doing so will either cause compile failures or runtime failures.
>>
>> Adding
>> select PCI_OPTION_ROM_RUN_VM86
>> below
>> config CPU_AMD_GEODELX
>> did not work out for me.
>
> Sorry I missed this.
>
> VSA requires the GDT that is in vm86.c. VSA loads similar to an option 
> ROM so the loader does go into VM86 mode. All the other stuff like 
> interrupt support and PCI BIOS isn't needed by VSA. I think that the 
> GDT at the top of vm86.c can be moved to a header file, gdt.h or 
> something like that.

northbridge/amd/geodelx/vsmsetup.c uses 
util/x86emu/vm86.c:setup_realmode_idt() but it seems most/all of the 
setup there is not needed at all for VSA. Pulling in setup_realmode_idt 
pulls in the rest of vm86 through direct and indirect dependencies.

> Care to make a patch? :)

Reduce the amount of compilation errors for Geode LX targets if x86emu 
or no emulation is selected instead of vm86.
Factor out GDT code from vm86.c to vm86_gdt.c

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

Index: LinuxBIOSv3-vsa_gdt/northbridge/amd/geodelx/Makefile
===================================================================
--- LinuxBIOSv3-vsa_gdt/northbridge/amd/geodelx/Makefile	(revision 611)
+++ LinuxBIOSv3-vsa_gdt/northbridge/amd/geodelx/Makefile	(working copy)
@@ -22,6 +22,7 @@
 ifeq ($(CONFIG_NORTHBRIDGE_AMD_GEODELX),y)
 
 STAGE2_CHIPSET_OBJ += $(obj)/northbridge/amd/geodelx/geodelx.o \
-		      $(obj)/northbridge/amd/geodelx/vsmsetup.o
+		      $(obj)/northbridge/amd/geodelx/vsmsetup.o \
+		      $(obj)/util/x86emu/vm86_gdt.o
 
 endif
Index: LinuxBIOSv3-vsa_gdt/util/x86emu/pcbios/pcibios.c
===================================================================
--- LinuxBIOSv3-vsa_gdt/util/x86emu/pcbios/pcibios.c	(revision 611)
+++ LinuxBIOSv3-vsa_gdt/util/x86emu/pcbios/pcibios.c	(working copy)
@@ -61,7 +61,7 @@
 		break;
 	case FIND_PCI_DEVICE:
 		/* FixME: support SI != 0 */
-		dev = dev_find_device(X86_DX, X86_CX, dev);
+		dev = dev_find_pci_device(X86_DX, X86_CX, dev);
 		if (dev != 0) {
 			X86_BH = dev->bus->secondary;
 			X86_BL = dev->path.u.pci.devfn;
Index: LinuxBIOSv3-vsa_gdt/util/x86emu/vm86_gdt.c
===================================================================
--- LinuxBIOSv3-vsa_gdt/util/x86emu/vm86_gdt.c	(revision 0)
+++ LinuxBIOSv3-vsa_gdt/util/x86emu/vm86_gdt.c	(revision 0)
@@ -0,0 +1,95 @@
+/*
+ *  Erik Arjan Hendriks <hendriks at lanl.gov>
+ *  Copyright (C) 2000 Scyld.
+ *  Copyright (C) 2000 Scyld Computing Corporation
+ *  Copyright (C) 2001 University of California.  LA-CC Number 01-67.
+ *  Copyright (C) 2005 Nick.Barker9 at btinternet.com
+ *  Copyright (C) 2007 coresystems GmbH
+ *
+ *  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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+
+/* Declare a temporary global descriptor table - 
+ * necessary because the core part of the bios 
+ * no longer sets up any 16 bit segments 
+ */
+
+__asm__ (
+	/* pointer to original gdt */
+	"	.globl gdtarg\n"
+	"gdtarg:			\n"
+	"	.word	gdt_limit	\n"
+	"	.long	gdtptr	       	\n"		
+
+	/* compute the table limit */
+	"__mygdt_limit = __mygdt_end - __mygdt - 1	\n"
+	"	.globl __mygdtaddr\n"
+	"__mygdtaddr:			\n"
+	"	.word	__mygdt_limit  	\n"
+	"	.long	__mygdt	       	\n"
+
+	"	.globl __mygdt\n"
+	"__mygdt: 		       	\n"
+	/* selgdt 0, unused */
+	"	.word	0x0000, 0x0000	\n"
+	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
+
+	/* selgdt 8, unused */
+	"	.word	0x0000, 0x0000	       	\n"
+	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
+
+	/* selgdt 0x10, flat code segment */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0x00, 0x9b, 0xcf, 0x00	\n"	
+
+	/* selgdt 0x18, flat data segment */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0x00, 0x93, 0xcf, 0x00	\n"
+
+	/* selgdt 0x20, unused */
+	"	.word	0x0000, 0x0000	       	\n"
+	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
+
+        /* selgdt 0x28 16-bit 64k code at 0x00000000 */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0, 0x9a, 0, 0	       	\n"
+
+	/* selgdt 0x30 16-bit 64k data at 0x00000000 */
+	"	.word	0xffff, 0x0000	       	\n"
+	"	.byte	0, 0x92, 0, 0	       	\n"
+
+	"__mygdt_end:				\n"
+
+	/* FIXME: This does probably not belong here */
+	"	.globl idtarg\n"
+	"idtarg:\n"
+	"	.word   _idt_end - _idt - 1\n"     /* limit */
+	"	.long   _idt\n"
+	"	.word   0\n"
+	"_idt:\n"
+	"	.fill   20, 8, 0\n" //       # idt is unitiailzed
+	"_idt_end:\n"
+
+	/* Declare a pointer to where our idt is going to be i.e. at mem zero */
+	"	.globl __myidt\n"
+	 "__myidt:		\n"
+	 /* 16-bit limit */
+	 "	.word 1023	\n"
+	 /* 24-bit base */
+	 "	.long 0		\n"
+	 "	.word 0		\n"
+);
Index: LinuxBIOSv3-vsa_gdt/util/x86emu/vm86.c
===================================================================
--- LinuxBIOSv3-vsa_gdt/util/x86emu/vm86.c	(revision 611)
+++ LinuxBIOSv3-vsa_gdt/util/x86emu/vm86.c	(working copy)
@@ -30,77 +30,6 @@
 #include <io.h>
 
 
-/* Declare a temporary global descriptor table - 
- * necessary because the core part of the bios 
- * no longer sets up any 16 bit segments 
- */
-
-__asm__ (
-	/* pointer to original gdt */
-	"	.globl gdtarg\n"
-	"gdtarg:			\n"
-	"	.word	gdt_limit	\n"
-	"	.long	gdtptr	       	\n"		
-
-	/* compute the table limit */
-	"__mygdt_limit = __mygdt_end - __mygdt - 1	\n"
-	"	.globl __mygdtaddr\n"
-	"__mygdtaddr:			\n"
-	"	.word	__mygdt_limit  	\n"
-	"	.long	__mygdt	       	\n"
-
-	"	.globl __mygdt\n"
-	"__mygdt: 		       	\n"
-	/* selgdt 0, unused */
-	"	.word	0x0000, 0x0000	\n"
-	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
-
-	/* selgdt 8, unused */
-	"	.word	0x0000, 0x0000	       	\n"
-	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
-
-	/* selgdt 0x10, flat code segment */
-	"	.word	0xffff, 0x0000	       	\n"
-	"	.byte	0x00, 0x9b, 0xcf, 0x00	\n"	
-
-	/* selgdt 0x18, flat data segment */
-	"	.word	0xffff, 0x0000	       	\n"
-	"	.byte	0x00, 0x93, 0xcf, 0x00	\n"
-
-	/* selgdt 0x20, unused */
-	"	.word	0x0000, 0x0000	       	\n"
-	"	.byte	0x00, 0x00, 0x00, 0x00	\n"
-
-        /* selgdt 0x28 16-bit 64k code at 0x00000000 */
-	"	.word	0xffff, 0x0000	       	\n"
-	"	.byte	0, 0x9a, 0, 0	       	\n"
-
-	/* selgdt 0x30 16-bit 64k data at 0x00000000 */
-	"	.word	0xffff, 0x0000	       	\n"
-	"	.byte	0, 0x92, 0, 0	       	\n"
-
-	"__mygdt_end:				\n"
-
-	/* FIXME: This does probably not belong here */
-	"	.globl idtarg\n"
-	"idtarg:\n"
-	"	.word   _idt_end - _idt - 1\n"     /* limit */
-	"	.long   _idt\n"
-	"	.word   0\n"
-	"_idt:\n"
-	"	.fill   20, 8, 0\n" //       # idt is unitiailzed
-	"_idt_end:\n"
-
-	/* Declare a pointer to where our idt is going to be i.e. at mem zero */
-	"	.globl __myidt\n"
-	 "__myidt:		\n"
-	 /* 16-bit limit */
-	 "	.word 1023	\n"
-	 /* 24-bit base */
-	 "	.long 0		\n"
-	 "	.word 0		\n"
-);
-
 /* The address arguments to this function are PHYSICAL ADDRESSES */ 
 static void real_mode_switch_call_vga(unsigned long devfn)
 {
Index: LinuxBIOSv3-vsa_gdt/util/x86emu/Makefile
===================================================================
--- LinuxBIOSv3-vsa_gdt/util/x86emu/Makefile	(revision 611)
+++ LinuxBIOSv3-vsa_gdt/util/x86emu/Makefile	(working copy)
@@ -20,7 +20,7 @@
 
 X86EMU_OBJ  = debug.o decode.o fpu.o ops.o ops2.o prim_ops.o sys.o
 BIOSEMU_OBJ = biosemu.o pcbios/pcibios.o
-VM86_OBJ    = vm86.o
+VM86_OBJ    = vm86.o vm86_gdt.o
 
 ifeq ($(CONFIG_PCI_OPTION_ROM_RUN_X86EMU),y)
 LIBX86EMU_OBJS = $(patsubst %,$(obj)/util/x86emu/x86emu/%,$(X86EMU_OBJ)) \


-- 
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