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linux-sg2042
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i386: paravirt boot sequence 

This patch uses the updated boot protocol to do paravirtualized boot.
If the boot version is >= 2.07, then it will do two things:

 1. Check the bootparams loadflags to see if we should reload the
    segment registers and clear interrupts.  This is appropriate
    for normal native boot and some paravirtualized environments, but
    inapproprate for others.

 2. Check the hardware architecture, and dispatch to the appropriate
    kernel entrypoint.  If the bootloader doesn't set this, then we
    simply do the normal boot sequence.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rusty Russell 2007-10-21 16:41:35 -07:00 committed by Linus Torvalds
parent 214541d1f3
commit a24e785111
4 changed files with 63 additions and 6 deletions
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15
arch/x86/boot/compressed/head_32.S
View File

@ -27,13 +27,22 @@
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/boot.h>
#include <asm/asm-offsets.h>
.section ".text.head","ax",@progbits
.globl startup_32
startup_32:
cld
cli
/* check to see if KEEP_SEGMENTS flag is meaningful */
cmpw $0x207, BP_version(%esi)
jb 1f
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
* us to not reload segments */
testb $(1<<6), BP_loadflags(%esi)
jnz 2f
1: cli
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
@ -41,6 +50,8 @@ startup_32:
movl %eax,%gs
movl %eax,%ss
2: cld
/* Calculate the delta between where we were compiled to run
* at and where we were actually loaded at. This can only be done
* with a short local call on x86. Nothing else will tell us what

3
arch/x86/boot/compressed/misc_32.c
View File

@ -247,6 +247,9 @@ static void putstr(const char *s)
int x,y,pos;
char c;
if (RM_SCREEN_INFO.orig_video_mode == 0 && lines == 0 && cols == 0)
return;
x = RM_SCREEN_INFO.orig_x;
y = RM_SCREEN_INFO.orig_y;

7
arch/x86/boot/header.S
View File

@ -119,7 +119,7 @@ _start:
# Part 2 of the header, from the old setup.S
.ascii "HdrS" # header signature
.word 0x0206 # header version number (>= 0x0105)
.word 0x0207 # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
.globl realmode_swtch
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
@ -214,6 +214,11 @@ cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
#added with boot protocol
#version 2.06
hardware_subarch: .long 0 # subarchitecture, added with 2.07
# default to 0 for normal x86 PC
hardware_subarch_data: .quad 0
# End of setup header #####################################################
.section ".inittext", "ax"

44
arch/x86/kernel/head_32.S
View File

@ -79,22 +79,30 @@ INIT_MAP_BEYOND_END = BOOTBITMAP_SIZE + (PAGE_TABLE_SIZE + ALLOCATOR_SLOP)*PAGE_
*/
.section .text.head,"ax",@progbits
ENTRY(startup_32)
/* check to see if KEEP_SEGMENTS flag is meaningful */
cmpw $0x207, BP_version(%esi)
jb 1f
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
us to not reload segments */
testb $(1<<6), BP_loadflags(%esi)
jnz 2f
/*
* Set segments to known values.
*/
cld
lgdt boot_gdt_descr - __PAGE_OFFSET
1: lgdt boot_gdt_descr - __PAGE_OFFSET
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
2:
/*
* Clear BSS first so that there are no surprises...
* No need to cld as DF is already clear from cld above...
*/
cld
xorl %eax,%eax
movl $__bss_start - __PAGE_OFFSET,%edi
movl $__bss_stop - __PAGE_OFFSET,%ecx
@ -128,6 +136,35 @@ ENTRY(startup_32)
movsl
1:
#ifdef CONFIG_PARAVIRT
cmpw $0x207, (boot_params + BP_version - __PAGE_OFFSET)
jb default_entry
/* Paravirt-compatible boot parameters. Look to see what architecture
we're booting under. */
movl (boot_params + BP_hardware_subarch - __PAGE_OFFSET), %eax
cmpl $num_subarch_entries, %eax
jae bad_subarch
movl subarch_entries - __PAGE_OFFSET(,%eax,4), %eax
subl $__PAGE_OFFSET, %eax
jmp *%eax
bad_subarch:
WEAK(lguest_entry)
WEAK(xen_entry)
/* Unknown implementation; there's really
nothing we can do at this point. */
ud2a
.data
subarch_entries:
.long default_entry /* normal x86/PC */
.long lguest_entry /* lguest hypervisor */
.long xen_entry /* Xen hypervisor */
num_subarch_entries = (. - subarch_entries) / 4
.previous
#endif /* CONFIG_PARAVIRT */
/*
* Initialize page tables. This creates a PDE and a set of page
* tables, which are located immediately beyond _end. The variable
@ -140,6 +177,7 @@ ENTRY(startup_32)
*/
page_pde_offset = (__PAGE_OFFSET >> 20);
default_entry:
movl $(pg0 - __PAGE_OFFSET), %edi
movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
movl $0x007, %eax /* 0x007 = PRESENT+RW+USER */