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Diffstat (limited to 'arch/x86/kernel/head64.c')
-rw-r--r--arch/x86/kernel/head64.c78
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