2 * prepare to run common code
4 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
7 #include <linux/init.h>
8 #include <linux/linkage.h>
9 #include <linux/types.h>
10 #include <linux/kernel.h>
11 #include <linux/string.h>
12 #include <linux/percpu.h>
13 #include <linux/start_kernel.h>
15 #include <asm/processor.h>
16 #include <asm/proto.h>
18 #include <asm/setup.h>
20 #include <asm/pgtable.h>
21 #include <asm/tlbflush.h>
22 #include <asm/sections.h>
23 #include <asm/kdebug.h>
25 #include <asm/bios_ebda.h>
27 static void __init zap_identity_mappings(void)
29 pgd_t *pgd = pgd_offset_k(0UL);
34 /* Don't add a printk in there. printk relies on the PDA which is not initialized
36 static void __init clear_bss(void)
38 memset(__bss_start, 0,
39 (unsigned long) __bss_stop - (unsigned long) __bss_start);
42 static void __init copy_bootdata(char *real_mode_data)
46 memcpy(&boot_params, real_mode_data, sizeof boot_params);
47 if (boot_params.hdr.cmd_line_ptr) {
48 command_line = __va(boot_params.hdr.cmd_line_ptr);
49 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
53 #define BIOS_LOWMEM_KILOBYTES 0x413
56 * The BIOS places the EBDA/XBDA at the top of conventional
57 * memory, and usually decreases the reported amount of
58 * conventional memory (int 0x12) too. This also contains a
59 * workaround for Dell systems that neglect to reserve EBDA.
60 * The same workaround also avoids a problem with the AMD768MPX
61 * chipset: reserve a page before VGA to prevent PCI prefetch
62 * into it (errata #56). Usually the page is reserved anyways,
63 * unless you have no PS/2 mouse plugged in.
65 static void __init reserve_ebda_region(void)
67 unsigned int lowmem, ebda_addr;
69 /* To determine the position of the EBDA and the */
70 /* end of conventional memory, we need to look at */
71 /* the BIOS data area. In a paravirtual environment */
72 /* that area is absent. We'll just have to assume */
73 /* that the paravirt case can handle memory setup */
74 /* correctly, without our help. */
75 if (paravirt_enabled())
78 /* end of low (conventional) memory */
79 lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
82 /* start of EBDA area */
83 ebda_addr = get_bios_ebda();
85 /* Fixup: bios puts an EBDA in the top 64K segment */
86 /* of conventional memory, but does not adjust lowmem. */
87 if ((lowmem - ebda_addr) <= 0x10000)
90 /* Fixup: bios does not report an EBDA at all. */
91 /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */
92 if ((ebda_addr == 0) && (lowmem >= 0x9f000))
95 /* Paranoia: should never happen, but... */
96 if ((lowmem == 0) || (lowmem >= 0x100000))
99 /* reserve all memory between lowmem and the 1MB mark */
100 reserve_early(lowmem, 0x100000, "BIOS reserved");
103 void __init x86_64_start_kernel(char * real_mode_data)
108 * Build-time sanity checks on the kernel image and module
109 * area mappings. (these are purely build-time and produce no code)
111 BUILD_BUG_ON(MODULES_VADDR < KERNEL_IMAGE_START);
112 BUILD_BUG_ON(MODULES_VADDR-KERNEL_IMAGE_START < KERNEL_IMAGE_SIZE);
113 BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
114 BUILD_BUG_ON((KERNEL_IMAGE_START & ~PMD_MASK) != 0);
115 BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
116 BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
117 BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
118 (__START_KERNEL & PGDIR_MASK)));
120 /* clear bss before set_intr_gate with early_idt_handler */
123 /* Make NULL pointers segfault */
124 zap_identity_mappings();
126 /* Cleanup the over mapped high alias */
129 for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
130 #ifdef CONFIG_EARLY_PRINTK
131 set_intr_gate(i, &early_idt_handlers[i]);
133 set_intr_gate(i, early_idt_handler);
136 load_idt((const struct desc_ptr *)&idt_descr);
138 early_printk("Kernel alive\n");
140 for (i = 0; i < NR_CPUS; i++)
141 cpu_pda(i) = &boot_cpu_pda[i];
144 copy_bootdata(__va(real_mode_data));
146 reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
148 #ifdef CONFIG_BLK_DEV_INITRD
150 if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
151 unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
152 unsigned long ramdisk_size = boot_params.hdr.ramdisk_size;
153 unsigned long ramdisk_end = ramdisk_image + ramdisk_size;
154 reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
158 reserve_ebda_region();
161 * At this point everything still needed from the boot loader
162 * or BIOS or kernel text should be early reserved or marked not
163 * RAM in e820. All other memory is free game.