diff options
Diffstat (limited to 'arch/x86/kernel/head64.c')
| -rw-r--r-- | arch/x86/kernel/head64.c | 78 |
1 files changed, 57 insertions, 21 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index ad2440832de..d6d54faa84d 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -49,39 +49,75 @@ static void __init copy_bootdata(char *real_mode_data) } } -#define EBDA_ADDR_POINTER 0x40E +#define BIOS_EBDA_SEGMENT 0x40E +#define BIOS_LOWMEM_KILOBYTES 0x413 -static __init void reserve_ebda(void) +/* + * The BIOS places the EBDA/XBDA at the top of conventional + * memory, and usually decreases the reported amount of + * conventional memory (int 0x12) too. This also contains a + * workaround for Dell systems that neglect to reserve EBDA. + * The same workaround also avoids a problem with the AMD768MPX + * chipset: reserve a page before VGA to prevent PCI prefetch + * into it (errata #56). Usually the page is reserved anyways, + * unless you have no PS/2 mouse plugged in. + */ +static void __init reserve_ebda_region(void) { - unsigned ebda_addr, ebda_size; + unsigned int lowmem, ebda_addr; + + /* To determine the position of the EBDA and the */ + /* end of conventional memory, we need to look at */ + /* the BIOS data area. In a paravirtual environment */ + /* that area is absent. We'll just have to assume */ + /* that the paravirt case can handle memory setup */ + /* correctly, without our help. */ + if (paravirt_enabled()) + return; - /* - * there is a real-mode segmented pointer pointing to the - * 4K EBDA area at 0x40E - */ - ebda_addr = *(unsigned short *)__va(EBDA_ADDR_POINTER); + /* end of low (conventional) memory */ + lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); + lowmem <<= 10; + + /* start of EBDA area */ + ebda_addr = *(unsigned short *)__va(BIOS_EBDA_SEGMENT); ebda_addr <<= 4; - if (!ebda_addr) - return; + /* Fixup: bios puts an EBDA in the top 64K segment */ + /* of conventional memory, but does not adjust lowmem. */ + if ((lowmem - ebda_addr) <= 0x10000) + lowmem = ebda_addr; - ebda_size = *(unsigned short *)__va(ebda_addr); + /* Fixup: bios does not report an EBDA at all. */ + /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */ + if ((ebda_addr == 0) && (lowmem >= 0x9f000)) + lowmem = 0x9f000; - /* Round EBDA up to pages */ - if (ebda_size == 0) - ebda_size = 1; - ebda_size <<= 10; - ebda_size = round_up(ebda_size + (ebda_addr & ~PAGE_MASK), PAGE_SIZE); - if (ebda_size > 64*1024) - ebda_size = 64*1024; + /* Paranoia: should never happen, but... */ + if ((lowmem == 0) || (lowmem >= 0x100000)) + lowmem = 0x9f000; - reserve_early(ebda_addr, ebda_addr + ebda_size, "EBDA"); + /* reserve all memory between lowmem and the 1MB mark */ + reserve_early(lowmem, 0x100000, "BIOS reserved"); } void __init x86_64_start_kernel(char * real_mode_data) { int i; + /* + * Build-time sanity checks on the kernel image and module + * area mappings. (these are purely build-time and produce no code) + */ + BUILD_BUG_ON(MODULES_VADDR < KERNEL_IMAGE_START); + BUILD_BUG_ON(MODULES_VADDR-KERNEL_IMAGE_START < KERNEL_IMAGE_SIZE); + BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE); + BUILD_BUG_ON((KERNEL_IMAGE_START & ~PMD_MASK) != 0); + BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0); + BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL)); + BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == + (__START_KERNEL & PGDIR_MASK))); + /* clear bss before set_intr_gate with early_idt_handler */ clear_bss(); @@ -91,7 +127,7 @@ void __init x86_64_start_kernel(char * real_mode_data) /* Cleanup the over mapped high alias */ cleanup_highmap(); - for (i = 0; i < IDT_ENTRIES; i++) { + for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) { #ifdef CONFIG_EARLY_PRINTK set_intr_gate(i, &early_idt_handlers[i]); #else @@ -118,7 +154,7 @@ void __init x86_64_start_kernel(char * real_mode_data) reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); } - reserve_ebda(); + reserve_ebda_region(); /* * At this point everything still needed from the boot loader |