diff options
Diffstat (limited to 'arch/x86/kernel/head64.c')
| -rw-r--r-- | arch/x86/kernel/head64.c | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index b684552347df..269a6b481fe6 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -55,12 +55,30 @@ static void __init copy_bootdata(char *real_mode_data) /* * The BIOS places the EBDA/XBDA at the top of conventional * memory, and usually decreases the reported amount of - * conventional memory (int 0x12) too. + * 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 __init void reserve_ebda(void) +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. */ +#ifdef CONFIG_PARAVIRT + if ((boot_params.hdr.version >= 0x207) && + (boot_params.hdr.hardware_subarch != 0)) { + return; + } +#endif + /* end of low (conventional) memory */ lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); lowmem <<= 10; @@ -80,8 +98,8 @@ static __init void reserve_ebda(void) lowmem = 0x9f000; /* Paranoia: should never happen, but... */ - if (lowmem >= 0x100000) - lowmem = 0xa0000; + if ((lowmem == 0) || (lowmem >= 0x100000)) + lowmem = 0x9f000; /* reserve all memory between lowmem and the 1MB mark */ reserve_early(lowmem, 0x100000, "BIOS reserved"); @@ -140,7 +158,7 @@ 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 |