x86/boot: Obsolete the MCA sys_desc_table

The kernel does not support the MCA bus anymroe, so mark sys_desc_table
as obsolete: remove any reference from the code together with the remaining
of MCA logic.

bloat-o-meter output:

  add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-55 (-55)
  function                                     old     new   delta
  i386_start_kernel                            128     119      -9
  setup_arch                                  1421    1375     -46

Signed-off-by: Paolo Pisati <p.pisati@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437409430-8491-1-git-send-email-p.pisati@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Documentation/x86/zero-page.txt

@@ -17,7 +17,8 @@ Offset	Proto	Name		Meaning
 				(struct ist_info)
 080/010	ALL	hd0_info	hd0 disk parameter, OBSOLETE!!
 090/010	ALL	hd1_info	hd1 disk parameter, OBSOLETE!!
-0A0/010	ALL	sys_desc_table	System description table (struct sys_desc_table)
+0A0/010	ALL	sys_desc_table	System description table (struct sys_desc_table),
+				OBSOLETE!!
 0B0/010	ALL	olpc_ofw_header	OLPC's OpenFirmware CIF and friends
 0C0/004	ALL	ext_ramdisk_image ramdisk_image high 32bits
 0C4/004	ALL	ext_ramdisk_size  ramdisk_size high 32bits

arch/x86/boot/Makefile

@@ -23,7 +23,7 @@ targets		+= fdimage fdimage144 fdimage288 image.iso mtools.conf
 subdir-		:= compressed
 
 setup-y		+= a20.o bioscall.o cmdline.o copy.o cpu.o cpuflags.o cpucheck.o
-setup-y		+= early_serial_console.o edd.o header.o main.o mca.o memory.o
+setup-y		+= early_serial_console.o edd.o header.o main.o memory.o
 setup-y		+= pm.o pmjump.o printf.o regs.o string.o tty.o video.o
 setup-y		+= video-mode.o version.o
 setup-$(CONFIG_X86_APM_BOOT) += apm.o

arch/x86/boot/boot.h

@@ -307,9 +307,6 @@ void query_edd(void);
 /* header.S */
 void __attribute__((noreturn)) die(void);
 
-/* mca.c */
-int query_mca(void);
-
 /* memory.c */
 int detect_memory(void);
 

arch/x86/boot/compressed/eboot.c

@@ -1041,7 +1041,6 @@ void setup_graphics(struct boot_params *boot_params)
 struct boot_params *make_boot_params(struct efi_config *c)
 {
 	struct boot_params *boot_params;
-	struct sys_desc_table *sdt;
 	struct apm_bios_info *bi;
 	struct setup_header *hdr;
 	struct efi_info *efi;
@@ -1089,7 +1088,6 @@ struct boot_params *make_boot_params(struct efi_config *c)
 	hdr = &boot_params->hdr;
 	efi = &boot_params->efi_info;
 	bi = &boot_params->apm_bios_info;
-	sdt = &boot_params->sys_desc_table;
 
 	/* Copy the second sector to boot_params */
 	memcpy(&hdr->jump, image->image_base + 512, 512);
@@ -1118,8 +1116,6 @@ struct boot_params *make_boot_params(struct efi_config *c)
 	/* Clear APM BIOS info */
 	memset(bi, 0, sizeof(*bi));
 
-	memset(sdt, 0, sizeof(*sdt));
-
 	status = efi_parse_options(cmdline_ptr);
 	if (status != EFI_SUCCESS)
 		goto fail2;

arch/x86/boot/main.c

@@ -161,9 +161,6 @@ void main(void)
 	/* Set keyboard repeat rate (why?) and query the lock flags */
 	keyboard_init();
 
-	/* Query MCA information */
-	query_mca();
-
 	/* Query Intel SpeedStep (IST) information */
 	query_ist();
 

arch/x86/boot/mca.c

@@ -1,38 +0,0 @@
-/* -*- linux-c -*- ------------------------------------------------------- *
- *
- *   Copyright (C) 1991, 1992 Linus Torvalds
- *   Copyright 2007 rPath, Inc. - All Rights Reserved
- *   Copyright 2009 Intel Corporation; author H. Peter Anvin
- *
- *   This file is part of the Linux kernel, and is made available under
- *   the terms of the GNU General Public License version 2.
- *
- * ----------------------------------------------------------------------- */
-
-/*
- * Get the MCA system description table
- */
-
-#include "boot.h"
-
-int query_mca(void)
-{
-	struct biosregs ireg, oreg;
-	u16 len;
-
-	initregs(&ireg);
-	ireg.ah = 0xc0;
-	intcall(0x15, &ireg, &oreg);
-
-	if (oreg.eflags & X86_EFLAGS_CF)
-		return -1;	/* No MCA present */
-
-	set_fs(oreg.es);
-	len = rdfs16(oreg.bx);
-
-	if (len > sizeof(boot_params.sys_desc_table))
-		len = sizeof(boot_params.sys_desc_table);
-
-	copy_from_fs(&boot_params.sys_desc_table, oreg.bx, len);
-	return 0;
-}

arch/x86/include/asm/processor.h

@@ -647,14 +647,6 @@ static inline void update_debugctlmsr(unsigned long debugctlmsr)
 
 extern void set_task_blockstep(struct task_struct *task, bool on);
 
-/*
- * from system description table in BIOS. Mostly for MCA use, but
- * others may find it useful:
- */
-extern unsigned int		machine_id;
-extern unsigned int		machine_submodel_id;
-extern unsigned int		BIOS_revision;
-
 /* Boot loader type from the setup header: */
 extern int			bootloader_type;
 extern int			bootloader_version;

arch/x86/include/uapi/asm/bootparam.h

@@ -120,7 +120,7 @@ struct boot_params {
 	__u8  _pad3[16];				/* 0x070 */
 	__u8  hd0_info[16];	/* obsolete! */		/* 0x080 */
 	__u8  hd1_info[16];	/* obsolete! */		/* 0x090 */
-	struct sys_desc_table sys_desc_table;		/* 0x0a0 */
+	struct sys_desc_table sys_desc_table; /* obsolete! */	/* 0x0a0 */
 	struct olpc_ofw_header olpc_ofw_header;		/* 0x0b0 */
 	__u32 ext_ramdisk_image;			/* 0x0c0 */
 	__u32 ext_ramdisk_size;				/* 0x0c4 */

arch/x86/kernel/kexec-bzimage64.c

@@ -223,9 +223,6 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
 	memset(&params->hd0_info, 0, sizeof(params->hd0_info));
 	memset(&params->hd1_info, 0, sizeof(params->hd1_info));
 
-	/* Default sysdesc table */
-	params->sys_desc_table.length = 0;
-
 	if (image->type == KEXEC_TYPE_CRASH) {
 		ret = crash_setup_memmap_entries(image, params);
 		if (ret)

arch/x86/kernel/setup.c

@@ -916,11 +916,6 @@ void __init setup_arch(char **cmdline_p)
 #ifdef CONFIG_X86_32
 	apm_info.bios = boot_params.apm_bios_info;
 	ist_info = boot_params.ist_info;
-	if (boot_params.sys_desc_table.length != 0) {
-		machine_id = boot_params.sys_desc_table.table[0];
-		machine_submodel_id = boot_params.sys_desc_table.table[1];
-		BIOS_revision = boot_params.sys_desc_table.table[2];
-	}
 #endif
 	saved_video_mode = boot_params.hdr.vid_mode;
 	bootloader_type = boot_params.hdr.type_of_loader;