Reduce the number of global variables

In preparation for strictly limiting the list of variables that are
exported (global) in the core, delete any unused variables, rewrite
variable declarations in C that are not referenced by asm and delete
files that are no longer included in other asm files.

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

16 files changed, 28 insertions, 270 deletions

diff --git a/com32/elflink/ldlinux/readconfig.c b/com32/elflink/ldlinux/readconfig.c
index 64c20a05..705ffa8a 100644
--- a/com32/elflink/ldlinux/readconfig.c
+++ b/com32/elflink/ldlinux/readconfig.c
@@ -718,7 +718,7 @@ extern uint8_t FlowInput;
 extern uint8_t FlowOutput;
 extern uint16_t SerialPort;
 extern uint16_t BaudDivisor;
-extern uint8_t SerialNotice;
+static uint8_t SerialNotice = 1;
 
 #define DEFAULT_BAUD	9600
 #define BAUD_DIVISOR	115200
diff --git a/com32/include/syslinux/features.h b/com32/include/syslinux/features.h
deleted file mode 100644
index d25d08d5..00000000
--- a/com32/include/syslinux/features.h
+++ /dev/null
@@ -1,48 +0,0 @@
-/* ----------------------------------------------------------------------- *
- *
- *   Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
- *
- *   Permission is hereby granted, free of charge, to any person
- *   obtaining a copy of this software and associated documentation
- *   files (the "Software"), to deal in the Software without
- *   restriction, including without limitation the rights to use,
- *   copy, modify, merge, publish, distribute, sublicense, and/or
- *   sell copies of the Software, and to permit persons to whom
- *   the Software is furnished to do so, subject to the following
- *   conditions:
- *
- *   The above copyright notice and this permission notice shall
- *   be included in all copies or substantial portions of the Software.
- *
- *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
- *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
- *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
- *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
- *   OTHER DEALINGS IN THE SOFTWARE.
- *
- * ----------------------------------------------------------------------- */
-
-#ifndef _SYSLINUX_FEATURES_H
-#define _SYSLINUX_FEATURES_H
-
-#define SYSLINUX_FEATURE_LOCAL_BOOT	(0*8+0)
-#define SYSLINUX_FEATURE_NOOP_IDLE	(0*8+1)
-
-extern uint8_t feature_flags;
-extern uint8_t feature_flags_len;
-
-static inline int syslinux_has_feature(unsigned int __flag)
-{
-    unsigned int __byte = __flag >> 3;
-    unsigned int __bit = __flag & 7;
-
-    if (__byte <= feature_flags_len)
-	return (feature_flags[__byte] >> __bit) & 1;
-    else
-	return 0;
-}
-
-#endif /* _SYSLINUX_FEATURE_H */
diff --git a/core/bios.inc b/core/bios.inc
index 33a3cd4c..2e150594 100644
--- a/core/bios.inc
+++ b/core/bios.inc
@@ -18,7 +18,6 @@
 
 %ifndef _BIOS_INC
 %define _BIOS_INC
-                global BIOS_fbm, BIOS_timer
 
 		; Interrupt vectors
 		absolute 4*1Ch
diff --git a/core/comboot.inc b/core/comboot.inc
index 4474cd37..2e690ff8 100644
--- a/core/comboot.inc
+++ b/core/comboot.inc
@@ -522,31 +522,13 @@ APIKeyFlag	db 0
 
 zero_string	db 0			; Empty, null-terminated string
 
-;
-; This is the feature flag array for INT 22h AX=0015h
-;
-; Note: PXELINUX clears the idle is noop flag if appropriate
-; in pxe_detect_nic_type
-;
-		global feature_flags, feature_flags_len
-feature_flags:
-		db 1			; Have local boot, idle is not noop
-feature_flags_len equ ($-feature_flags)
-
 err_notdos	db ': attempted DOS system call INT ',0
 err_comlarge	db 'COMBOOT image too large.', CR, LF, 0
 
-		global VGAFontSize, UserFont
-		alignz 2
-VGAFontSize	dw 16			; Defaults to 16 byte font
-UserFont	db 0			; Using a user-specified font
-
 		section .bss16
 		alignb 4
 DOSErrTramp	resd	33		; Error trampolines
 
-		global ConfigName
-ConfigName	resb	FILENAME_MAX
 %ifndef HAVE_CURRENTDIRNAME
 		global CurrentDirName
 CurrentDirName	resb	FILENAME_MAX
diff --git a/core/diskfs.inc b/core/diskfs.inc
index dcbc924a..9c9da267 100644
--- a/core/diskfs.inc
+++ b/core/diskfs.inc
@@ -91,24 +91,15 @@ auto_boot:
 		jmp kaboom
 
 		section .bss16
-		global CmdOptPtr, KbdMap
 		alignb 4
 ThisKbdTo	resd 1			; Temporary holder for KbdTimeout
 ThisTotalTo	resd 1			; Temporary holder for TotalTimeout
 KernelExtPtr	resw 1			; During search, final null pointer
-CmdOptPtr	resw 1			; Pointer to first option on cmd line
-KbdFlags	resb 1			; Check for keyboard escapes
 FuncFlag	resb 1			; Escape sequences received from keyboard
 KernelType	resb 1			; Kernel type, from vkernel, if known
-KbdMap		resb 256		; Keyboard map
 		global KernelName
 KernelName	resb FILENAME_MAX	; Mangled name for kernel
-		section .config
-		global PXERetry
-PXERetry	dw 0			; Extra PXE retries
 		section .data16
-		global SerialNotice
-SerialNotice	db 1			; Only print this once
 		global IPAppends, numIPAppends
 %if IS_PXELINUX
 		extern IPOption
diff --git a/core/font.c b/core/font.c
index 9e7aa8f2..38f03f58 100644
--- a/core/font.c
+++ b/core/font.c
@@ -26,6 +26,8 @@
 #include "graphics.h"
 #include "core.h"
 
+uint8_t UserFont = 0;		/* Using a user-specified font */
+
 __lowmem char fontbuf[8192];
 
 uint16_t GXPixCols = 1;		/* Graphics mode pixel columns */
diff --git a/core/fs/pxe/pxe.c b/core/fs/pxe/pxe.c
index 3cc64973..ee818ecd 100644
--- a/core/fs/pxe/pxe.c
+++ b/core/fs/pxe/pxe.c
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <core.h>
+#include <bios.h>
 #include <fs.h>
 #include <minmax.h>
 #include <sys/cpu.h>
@@ -644,7 +645,7 @@ static uint32_t pxe_getfssec(struct file *file, char *buf,
  *
  */
 static void __pxe_searchdir(const char *filename, struct file *file);
-extern uint16_t PXERetry;
+uint16_t PXERetry;
 
 static void pxe_searchdir(const char *filename, struct file *file)
 {
@@ -1270,9 +1271,9 @@ static const void *memory_scan(uintptr_t start, int (*func)(const void *))
 
 static const struct pxe_t *memory_scan_for_pxe_struct(void)
 {
-    extern uint16_t BIOS_fbm;  /* Starting segment */
+    uint16_t start = bios_fbm(); /* Starting segment */
 
-    return memory_scan(BIOS_fbm << 10, is_pxe);
+    return memory_scan(start << 10, is_pxe);
 }
 
 static const struct pxenv_t *memory_scan_for_pxenv_struct(void)
@@ -1677,11 +1678,11 @@ void unload_pxe(uint16_t flags)
 	uint16_t Status;	/* All calls have this as the first member */
     } unload_call;
 
-    dprintf("FBM before unload = %d\n", BIOS_fbm);
+    dprintf("FBM before unload = %d\n", bios_fbm());
 
     err = reset_pxe();
 
-    dprintf("FBM after reset_pxe = %d, err = %d\n", BIOS_fbm, err);
+    dprintf("FBM after reset_pxe = %d, err = %d\n", bios_fbm(), err);
 
     /* If we want to keep PXE around, we still need to reset it */
     if (flags || err)
@@ -1701,8 +1702,8 @@ void unload_pxe(uint16_t flags)
     }
 
     api = 0xff00;
-    if (real_base_mem <= BIOS_fbm) {  /* Sanity check */ 
-	dprintf("FBM %d < real_base_mem %d\n", BIOS_fbm, real_base_mem);
+    if (real_base_mem <= bios_fbm()) {  /* Sanity check */
+	dprintf("FBM %d < real_base_mem %d\n", bios_fbm(), real_base_mem);
 	goto cant_free;
     }
     api++;
@@ -1710,20 +1711,20 @@ void unload_pxe(uint16_t flags)
     /* Check that PXE actually unhooked the INT 0x1A chain */
     int_addr = (size_t)GET_PTR(*(far_ptr_t *)(4 * 0x1a));
     int_addr >>= 10;
-    if (int_addr >= real_base_mem || int_addr < BIOS_fbm) {
-	BIOS_fbm = real_base_mem;
-	dprintf("FBM after unload_pxe = %d\n", BIOS_fbm);
+    if (int_addr >= real_base_mem || int_addr < bios_fbm()) {
+	set_bios_fbm(real_base_mem);
+	dprintf("FBM after unload_pxe = %d\n", bios_fbm());
 	return;
     }
 
     dprintf("Can't free FBM, real_base_mem = %d, "
 	    "FBM = %d, INT 1A = %08x (%d)\n",
-	    real_base_mem, BIOS_fbm,
+	    real_base_mem, bios_fbm(),
 	    *(uint32_t *)(4 * 0x1a), int_addr);
 
 cant_free:
     printf("Failed to free base memory error %04x-%08x (%d/%dK)\n",
-	   api, *(uint32_t *)(4 * 0x1a), BIOS_fbm, real_base_mem);
+	   api, *(uint32_t *)(4 * 0x1a), bios_fbm(), real_base_mem);
     return;
 }
 
diff --git a/core/fs/pxe/pxe.h b/core/fs/pxe/pxe.h
index c754106d..d4377581 100644
--- a/core/fs/pxe/pxe.h
+++ b/core/fs/pxe/pxe.h
@@ -211,7 +211,6 @@ extern bool have_uuid;
 extern uint8_t uuid_type;
 extern uint8_t uuid[];
 
-extern uint16_t BIOS_fbm;
 extern const uint8_t TimeoutTable[];
 
 /*
diff --git a/core/graphics.c b/core/graphics.c
index bdf48a85..55d91d7e 100644
--- a/core/graphics.c
+++ b/core/graphics.c
@@ -28,6 +28,7 @@
 uint8_t UsingVGA = 0;
 uint16_t VGAPos;		/* Pointer into VGA memory */
 uint16_t *VGAFilePtr;		/* Pointer into VGAFileBuf */
+uint16_t VGAFontSize = 16;	/* Defaults to 16 byte font */
 
 char VGAFileBuf[VGA_FILE_BUF_SIZE]; /* Unmangled VGA image name */
 char VGAFileMBuf[FILENAME_MAX];	/* Mangled VGA image name */
diff --git a/core/highmem.inc b/core/highmem.inc
deleted file mode 100644
index ea386ffc..00000000
--- a/core/highmem.inc
+++ /dev/null
@@ -1,158 +0,0 @@
-;; -----------------------------------------------------------------------
-;;
-;;   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
-;;
-;;   This program is free software; you can redistribute it and/or modify
-;;   it under the terms of the GNU General Public License as published by
-;;   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
-;;   Boston MA 02111-1307, USA; either version 2 of the License, or
-;;   (at your option) any later version; incorporated herein by reference.
-;;
-;; -----------------------------------------------------------------------
-
-;;
-;; highmem.inc
-;;
-;; Probe for the size of high memory.  This can be overridden by a
-;; mem= command on the command line while booting a new kernel.
-;;
-
-		section .text16
-
-;
-; This is set up as a subroutine; it will set up the global variable
-; HighMemSize.  All registers are preserved.
-;
-highmemsize:
-		push es
-		pushfd
-		pushad
-
-		push cs
-		pop es
-
-;
-; First, try INT 15:E820 (get BIOS memory map)
-;
-; Note: we may have to scan this multiple times, because some (daft) BIOSes
-; report main memory as multiple contiguous ranges...
-;
-get_e820:
-		mov dword [E820Max],-(1 << 20)	; Max amount of high memory
-		mov dword [E820Mem],(1 << 20)	; End of detected high memory
-.start_over:
-		mov di,E820Buf
-		xor ax,ax
-		mov cx,10
-		rep stosw			; Clear buffer
-		xor ebx,ebx			; Start with first record
-		jmp short .do_e820		; Skip "at end" check first time!
-.int_loop:	and ebx,ebx			; If we're back at beginning...
-		jz .e820_done			; ... we're done
-.do_e820:	mov eax,0000E820h
-		mov edx,534D4150h		; "SMAP" backwards
-		xor ecx,ecx
-		mov cl,20			; ECX <- 20 (size of buffer)
-		mov di,E820Buf
-		int 15h
-		jnc .no_carry
-		; If carry, ebx == 0 means error, ebx != 0 means we're done
-		and ebx,ebx
-		jnz .e820_done
-		jmp no_e820
-.no_carry:
-		cmp eax,534D4150h
-		jne no_e820
-		cmp cx,20
-		jb no_e820
-
-;
-; Look for a memory block starting at <= 1 MB and continuing upward
-;
-		cmp dword [E820Buf+4], byte 0
-		ja .int_loop			; Start >= 4 GB?
-		mov eax, [E820Buf]
-		cmp dword [E820Buf+16],1
-		je .is_ram			; Is it memory?
-		;
-		; Non-memory range.  Remember this as a limit; some BIOSes get the length
-		; of primary RAM incorrect!
-		;
-.not_ram:
-		cmp eax, (1 << 20)
-		jb .int_loop			; Starts in lowmem region
-		cmp eax,[E820Max]
-		jae .int_loop			; Already above limit
-		mov [E820Max],eax		; Set limit
-		jmp .int_loop
-
-.is_ram:
-		cmp eax,[E820Mem]
-		ja .int_loop			; Not contiguous with our starting point
-		add eax,[E820Buf+8]
-		jc .overflow
-		cmp dword [E820Buf+12],0
-		je .nooverflow
-.overflow:
-		or eax,-1
-.nooverflow:
-		cmp eax,[E820Mem]
-		jbe .int_loop			; All is below our baseline
-		mov [E820Mem],eax
-		jmp .start_over			; Start over in case we find an adjacent range
-
-.e820_done:
-		mov eax,[E820Mem]
-		cmp eax,[E820Max]
-		jna .not_limited
-		mov eax,[E820Max]
-.not_limited:
-		cmp eax,(1 << 20)
-		ja got_highmem			; Did we actually find memory?
-		; otherwise fall through
-
-;
-; INT 15:E820 failed.  Try INT 15:E801.
-;
-no_e820:
-		mov ax,0e801h			; Query high memory (semi-recent)
-		int 15h
-		jc no_e801
-		cmp ax,3c00h
-		ja no_e801			; > 3C00h something's wrong with this call
-		jb e801_hole			; If memory hole we can only use low part
-
-		mov ax,bx
-		shl eax,16			; 64K chunks
-		add eax,(16 << 20)		; Add first 16M
-		jmp short got_highmem
-
-;
-; INT 15:E801 failed.  Try INT 15:88.
-;
-no_e801:
-		mov ah,88h			; Query high memory (oldest)
-		int 15h
-		cmp ax,14*1024			; Don't trust memory >15M
-		jna e801_hole
-		mov ax,14*1024
-e801_hole:
-		and eax,0ffffh
-		shl eax,10			; Convert from kilobytes
-		add eax,(1 << 20)		; First megabyte
-got_highmem:
-%if HIGHMEM_SLOP != 0
-		sub eax,HIGHMEM_SLOP
-%endif
-		mov [HighMemSize],eax
-		popad
-		popfd
-		pop es
-		ret				; Done!
-
-		section .bss16
-		alignb 4
-E820Buf		resd 5			; INT 15:E820 data buffer
-E820Mem		resd 1			; Memory detected by E820
-E820Max		resd 1			; Is E820 memory capped?
-; HighMemSize is defined in com32.inc
diff --git a/core/include/bios.h b/core/include/bios.h
index 42a9768c..d38f6692 100644
--- a/core/include/bios.h
+++ b/core/include/bios.h
@@ -35,6 +35,16 @@
 #define BIOS_magic	0x0472	/* BIOS reset magic */
 #define BIOS_vidrows	0x0484	/* Number of screen rows */
 
+static inline uint16_t bios_fbm(void)
+{
+	return *(volatile uint16_t *)BIOS_fbm;
+}
+
+static inline void set_bios_fbm(uint16_t mem)
+{
+	*(volatile uint16_t *)BIOS_fbm = mem;
+}
+
 #define serial_buf_size		4096
 #define IO_DELAY_PORT		0x80 /* Invalid port (we hope!) */
 
diff --git a/core/init.c b/core/init.c
index 26b4a191..ca9e413f 100644
--- a/core/init.c
+++ b/core/init.c
@@ -7,6 +7,7 @@
 static uint32_t min_lowmem_heap = 65536;
 extern char __lowmem_heap[];
 uint8_t KbdFlags;		/* Check for keyboard escapes */
+uint8_t KbdMap[256];		/* Keyboard map */
 
 static inline void check_escapes(void)
 {
diff --git a/core/isolinux.asm b/core/isolinux.asm
index 617003c6..8866298e 100644
--- a/core/isolinux.asm
+++ b/core/isolinux.asm
@@ -1202,24 +1202,15 @@ debug_tracer:	pushad
 %endif	; DEBUG_TRACERS
 
 		section .bss16
-		global CmdOptPtr, KbdMap
 		alignb 4
 ThisKbdTo	resd 1			; Temporary holder for KbdTimeout
 ThisTotalTo	resd 1			; Temporary holder for TotalTimeout
 KernelExtPtr	resw 1			; During search, final null pointer
-CmdOptPtr	resw 1			; Pointer to first option on cmd line
-KbdFlags	resb 1			; Check for keyboard escapes
 FuncFlag	resb 1			; Escape sequences received from keyboard
 KernelType	resb 1			; Kernel type, from vkernel, if known
-KbdMap		resb 256		; Keyboard map
 		global KernelName
 KernelName	resb FILENAME_MAX	; Mangled name for kernel
-		section .config
-		global PXERetry
-PXERetry	dw 0			; Extra PXE retries
 		section .data16
-		global SerialNotice
-SerialNotice	db 1			; Only print this once
 		global IPAppends, numIPAppends
 %if IS_PXELINUX
 		extern IPOption
diff --git a/core/kernel.inc b/core/kernel.inc
index 245cd6db..5e1c7a39 100644
--- a/core/kernel.inc
+++ b/core/kernel.inc
@@ -62,9 +62,6 @@ linux_fdctab	resb 12
 cmd_line_here	equ $			; F800 Should be out of the way
 		endstruc
 
-		global cmd_line
-cmd_line	equ core_real_mode + cmd_line_here
-
 ;
 ; Old kernel command line signature
 ;
diff --git a/core/layout.inc b/core/layout.inc
index 24843923..6d31b18e 100644
--- a/core/layout.inc
+++ b/core/layout.inc
@@ -52,7 +52,6 @@ LATEBSS_START	equ 0B800h
 ;
 ; 32-bit stack layout
 ;
-		global STACK32_LEN
 STACK32_LEN	equ 64*1024
 
 		section	.stack		nobits write align=4096
diff --git a/core/pxelinux.asm b/core/pxelinux.asm
index 63334ffa..097b856c 100644
--- a/core/pxelinux.asm
+++ b/core/pxelinux.asm
@@ -281,24 +281,15 @@ Kernel_EAX	resd 1
 Kernel_SI	resw 1
 
 		section .bss16
-		global CmdOptPtr, KbdMap
 		alignb 4
 ThisKbdTo	resd 1			; Temporary holder for KbdTimeout
 ThisTotalTo	resd 1			; Temporary holder for TotalTimeout
 KernelExtPtr	resw 1			; During search, final null pointer
-CmdOptPtrj	resw 1			; Pointer to first option on cmd line
-KbdFlags	resb 1			; Check for keyboard escapes
 FuncFlag	resb 1			; Escape sequences received from keyboard
 KernelType	resb 1			; Kernel type, from vkernel, if known
-KbdMap		resb 256		; Keyboard map
 		global KernelName
 KernelName	resb FILENAME_MAX	; Mangled name for kernel
-		section .config
-		global PXERetry
-PXERetry	dw 0			; Extra PXE retries
 		section .data16
-		global SerialNotice
-SerialNotice	db 1			; Only print this once
 		extern IPOption
 		global IPAppends, numIPAppends
 		alignz 2