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-rw-r--r--arch/x86/kernel/head_32.S44
1 files changed, 41 insertions, 3 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 39677965e161..00b1c2c56454 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -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 */