x86: extend e820 ealy_res support 32bit

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / head32.c

diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 3db0590589276e5ecbc1d74dd1331264bc414f11..c216d3c2a991a4236a9598b94d68c763c84fc065 100644 (file)
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -8,7 +8,83 @@
 #include <linux/init.h>
 #include <linux/start_kernel.h>
 
+#include <asm/setup.h>
+#include <asm/sections.h>
+#include <asm/e820.h>
+#include <asm/bios_ebda.h>
+
+#define BIOS_LOWMEM_KILOBYTES 0x413
+
+/*
+ * 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 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;
+
+       /* end of low (conventional) memory */
+       lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
+       lowmem <<= 10;
+
+       /* start of EBDA area */
+       ebda_addr = get_bios_ebda();
+
+       /* 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;
+
+       /* 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;
+
+       /* Paranoia: should never happen, but... */
+       if ((lowmem == 0) || (lowmem >= 0x100000))
+               lowmem = 0x9f000;
+
+       /* reserve all memory between lowmem and the 1MB mark */
+       reserve_early(lowmem, 0x100000, "BIOS reserved");
+}
+
 void __init i386_start_kernel(void)
 {
+       reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
+
+#ifdef CONFIG_BLK_DEV_INITRD
+       /* Reserve INITRD */
+       if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
+               u64 ramdisk_image = boot_params.hdr.ramdisk_image;
+               u64 ramdisk_size  = boot_params.hdr.ramdisk_size;
+               u64 ramdisk_end   = ramdisk_image + ramdisk_size;
+               reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
+       }
+#endif
+       reserve_early(__pa_symbol(&_end), init_pg_tables_end, "INIT_PG_TABLE");
+
+       reserve_ebda_region();
+
+       /*
+        * At this point everything still needed from the boot loader
+        * or BIOS or kernel text should be early reserved or marked not
+        * RAM in e820. All other memory is free game.
+        */
+
        start_kernel();
 }