x86: remove zImage support

Impact: obsolete feature removal

The zImage kernel format has been functionally unused for a very long
time.  It is just barely possible to build a modern kernel that still
fits within the zImage size limit, but it is highly unlikely that
anyone ever uses it.  Furthermore, although it is still supported by
most bootloaders, it has been at best poorly tested (or not tested at
all); some bootloaders are even known to not support zImage at all and
not having even noticed.

Also remove some really obsolete constants that no longer have any
meaning.

LKML-Reference: <49B703D4.1000008@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 9 insertions, 20 deletions

diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 7ccff4884a23..5d84d1c74e4c 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -24,12 +24,8 @@
 #include "boot.h"
 #include "offsets.h"
 
-SETUPSECTS      = 4                     /* default nr of setup-sectors */
 BOOTSEG         = 0x07C0                /* original address of boot-sector */
-SYSSEG          = DEF_SYSSEG            /* system loaded at 0x10000 (65536) */
-SYSSIZE         = DEF_SYSSIZE           /* system size: # of 16-byte clicks */
-                                        /* to be loaded */
-ROOT_DEV        = 0                     /* ROOT_DEV is now written by "build" */
+SYSSEG          = 0x1000                /* historical load address >> 4 */
 
 #ifndef SVGA_MODE
 #define SVGA_MODE ASK_VGA
@@ -97,12 +93,12 @@ bugger_off_msg:
         .section ".header", "a"
         .globl  hdr
 hdr:
-setup_sects:    .byte SETUPSECTS
+setup_sects:    .byte 0                 /* Filled in by build.c */
 root_flags:     .word ROOT_RDONLY
-syssize:        .long SYSSIZE
-ram_size:       .word RAMDISK
+syssize:        .long 0                 /* Filled in by build.c */
+ram_size:       .word 0                 /* Obsolete */
 vid_mode:       .word SVGA_MODE
-root_dev:       .word ROOT_DEV
+root_dev:       .word 0                 /* Filled in by build.c */
 boot_flag:      .word 0xAA55
 
         # offset 512, entry point
@@ -123,14 +119,15 @@ _start:
                                         # or else old loadlin-1.5 will fail)
                 .globl realmode_swtch
 realmode_swtch: .word   0, 0            # default_switch, SETUPSEG
-start_sys_seg:  .word   SYSSEG
+start_sys_seg:  .word   SYSSEG          # obsolete and meaningless, but just
+                                        # in case something decided to "use" it
                 .word   kernel_version-512 # pointing to kernel version string
                                         # above section of header is compatible
                                         # with loadlin-1.5 (header v1.5). Don't
                                         # change it.
 
-type_of_loader: .byte   0               # = 0, old one (LILO, Loadlin,
-                                        #      Bootlin, SYSLX, bootsect...)
+type_of_loader: .byte   0               # 0 means ancient bootloader, newer
+                                        # bootloaders know to change this.
                                         # See Documentation/i386/boot.txt for
                                         # assigned ids
 
@@ -142,11 +139,7 @@ CAN_USE_HEAP	= 0x80			# If set, the loader also has set
                                         # space behind setup.S can be used for
                                         # heap purposes.
                                         # Only the loader knows what is free
-#ifndef __BIG_KERNEL__
-                .byte   0
-#else
                 .byte   LOADED_HIGH
-#endif
 
 setup_move_size: .word  0x8000          # size to move, when setup is not
                                         # loaded at 0x90000. We will move setup
@@ -157,11 +150,7 @@ setup_move_size: .word  0x8000		# size to move, when setup is not
 
 code32_start:                           # here loaders can put a different
                                         # start address for 32-bit code.
-#ifndef __BIG_KERNEL__
-                .long   0x1000          #   0x1000 = default for zImage
-#else
                 .long   0x100000        # 0x100000 = default for big kernel
-#endif
 
 ramdisk_image:  .long   0               # address of loaded ramdisk image
                                         # Here the loader puts the 32-bit