core: let xfer_buf_seg, real_mode_seg be assigned by the linker

Use the linker to assign xfer_bug_seg and real_mode_seg.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/core/com32.inc b/core/com32.inc
index 3fa2d31..b198dac 100644 (file)
--- a/core/com32.inc
+++ b/core/com32.inc
@@ -86,7 +86,7 @@ com32_start:
                push dword core_cfarcall        ; Cfarcall entry point
                push dword core_farcall         ; Farcall entry point
                push dword (1 << 16)            ; 64K bounce buffer
-               push dword (xfer_buf_seg << 4)  ; Bounce buffer address
+               push dword core_xfer_buf        ; Bounce buffer address
                push dword core_intcall         ; Intcall entry point
                push dword command_line         ; Command line pointer
                push dword 7                    ; Argument count

diff --git a/core/conio.inc b/core/conio.inc
index 60d1fcb..5157e48 100644 (file)
--- a/core/conio.inc
+++ b/core/conio.inc
@@ -15,7 +15,7 @@
 ;; conio.inc
 ;;
 ;; Console I/O code, except:
-;;   writechr, writestr_early          - module-dependent
+;;   writechr, writestr_early  - module-dependent
 ;;   writestr, crlf            - writestr.inc
 ;;   writehex*                 - writehex.inc
 ;;

diff --git a/core/init.inc b/core/init.inc
index a3fe304..90c0293 100644 (file)
--- a/core/init.inc
+++ b/core/init.inc
@@ -64,11 +64,19 @@ check_escapes:
 ; NOTE: Linux doesn't use all of real_mode_seg, but we use the same
 ; segment for COMBOOT images, which can use all 64K
 ;
-dosram_k       equ (real_mode_seg+0x1000) >> 6 ; Minimum DOS memory (K)
                int 12h
-               cmp ax,dosram_k
+               mov dx,real_mode_seg + 0x1000
+               shr dx,6                
+               cmp ax,dx
                jae enough_ram
+               mov ax,dx
                mov si,err_noram
+               mov cl,10
+               div cl
+               add [si+err_noram.size-err_noram+2],ah
+               cbw
+               div cl
+               add [si+err_noram.size-err_noram],ax
                call writestr_early
                jmp kaboom
 enough_ram:
@@ -76,7 +84,7 @@ skip_checks:
 
                section .data16
 err_noram      db 'It appears your computer has less than '
-               asciidec dosram_k
+.size          db '000'
                db 'K of low ("DOS")'
                db CR, LF
                db 'RAM.  Syslinux needs at least this amount to boot.  If you get'
@@ -84,8 +92,8 @@ err_noram     db 'It appears your computer has less than '
                db 'this message in error, hold down the Ctrl key while'
                db CR, LF
                db 'booting, and I will take your word for it.', CR, LF, 0
-               section .text16
 
+               section .text16
 ;
 ; The code to decompress the PM code and initialize other segments.
 ;

diff --git a/core/isolinux.asm b/core/isolinux.asm
index d6be750..4a029c4 100644 (file)
--- a/core/isolinux.asm
+++ b/core/isolinux.asm
@@ -414,7 +414,7 @@ found_file:
                ; address (7C00h) is *not* 2K-sector-aligned, the safest
                ; way to deal with this is to load into the xfer_buf_seg
                ; and then copy the data in place.
-MaxLMA         equ xfer_buf_seg << 4
+MaxLMA         equ core_xfer_buf
 
                mov bx,(7C00h+SECTOR_SIZE) >> 4
                mov bp,[ImageSectors]

diff --git a/core/kernel.inc b/core/kernel.inc
index 3ac5af1..245cd6d 100644 (file)
--- a/core/kernel.inc
+++ b/core/kernel.inc
@@ -63,7 +63,7 @@ cmd_line_here equ $                   ; F800 Should be out of the way
                endstruc
 
                global cmd_line
-cmd_line       equ (real_mode_seg << 4) + cmd_line_here
+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 baf45b9..b769832 100644 (file)
--- a/core/layout.inc
+++ b/core/layout.inc
@@ -115,13 +115,6 @@ RBFG_brainfuck:    resb 2048               ; Bigger than an Ethernet packet...
 ; Keep the low-memory footprint as small as possible... overrun is a hard
 ; failure!
 ;
-; 0000h - main code/data segment (and BIOS segment)
-;
-; This stuff really should come from the linker...
-;
-               global  xfer_buf_seg, core_xfer_buf
-xfer_buf_seg   equ 2000h
-core_xfer_buf  equ xfer_buf_seg << 4
 
 serial_buf_size        equ 4096                ; Should be a power of 2
 
@@ -141,8 +134,24 @@ serial_buf_size    equ 4096                ; Should be a power of 2
 auxseg         resb aux_size
 
 ;
+; Transfer buffer segment: guaranteed to be aligned 64K, used for disk I/O
+; One symbol for the segment number, one for the absolute address
+;
+               extern  xfer_buf_seg
+               section .xfer_buf       write nobits align=65536
+               global  core_xfer_buf
+core_xfer_buf  resb 65536
+
+;
 ; Segment for the real mode code (needed as long as we have a in-kernel
 ; loader and/or COM16 support.
+; One symbol for the segment number, one for the absolute address
 ;
-real_mode_seg  equ xfer_buf_seg + 1000h
+               extern  real_mode_seg
+               section .real_mode      write nobits align=65536
+               global  core_real_mode
+core_real_mode resb 65536
+
 comboot_seg    equ real_mode_seg       ; COMBOOT image loading zone
+
+               section .text16

diff --git a/core/loadhigh.inc b/core/loadhigh.inc
index 63ab001..205c3e6 100644 (file)
--- a/core/loadhigh.inc
+++ b/core/loadhigh.inc
@@ -87,7 +87,7 @@ load_high:
                ja .overflow
 
                push esi                        ; <D> File handle/cluster pointer
-               mov esi,(xfer_buf_seg << 4)     ; Source address
+               mov esi,core_xfer_buf           ; Source address
                call bcopy                      ; Copy to high memory
                pop esi                         ; <D> File handle/cluster pointer
                popf                            ; <C> EOF status

diff --git a/core/runkernel.inc b/core/runkernel.inc
index 30177e8..f4dc28e 100644 (file)
--- a/core/runkernel.inc
+++ b/core/runkernel.inc
@@ -259,7 +259,7 @@ read_kernel:
                 shl si,9                       ; Convert to bytes
                 mov ecx,8000h                  ; 32K
                sub ecx,esi                     ; Number of bytes to copy
-               add esi,(real_mode_seg << 4)    ; Pointer to source
+               add esi,core_real_mode          ; Pointer to source
                 mov edi,free_high_memory       ; Copy to free high memory
 
                 call bcopy                     ; Transfer to high memory
@@ -359,7 +359,7 @@ setup_command_line:
                ; New cmdline protocol
                ; Store 32-bit (flat) pointer to command line
                ; This is the "high" location, since we have bzImage
-               mov dword [fs:su_cmd_line_ptr],(real_mode_seg << 4)+cmd_line_here
+               mov dword [fs:su_cmd_line_ptr],cmd_line
                mov word [HeapEnd],linux_stack
                mov word [fs:su_heapend],linux_stack-512
                jmp .setup_done
@@ -422,7 +422,7 @@ setup_move:
 ; Loading low: move real_mode stuff to 90000h, then move the kernel down
                mov eax,90000h
                stosd
-               mov eax,real_mode_seg << 4
+               mov eax,core_real_mode
                stosd
                movzx eax,word [CmdLineEnd]
                stosd

diff --git a/core/syslinux.ld b/core/syslinux.ld
index df7242e..f503920 100644 (file)
--- a/core/syslinux.ld
+++ b/core/syslinux.ld
@@ -226,9 +226,20 @@ SECTIONS
        __high_clear_len = __high_clear_end - __high_clear_start;
        __high_clear_dwords = (__high_clear_len + 3) >> 2;
 
+       /*
+        * Special 16-bit segments
+        */
+       . = ALIGN(65536);
+       .xfer_buf (NOLOAD) : {
+               *(.xfer_buf)
+       }
+       xfer_buf_seg = core_xfer_buf >> 4;
 
-       __assert_high = ASSERT(__high_clear_end <= core_xfer_buf,
-       "auxseg/lowmem region collides with xfer_buf_seg");
+       . = ALIGN(65536);
+       .real_mode (NOLOAD) : {
+               *(.real_mode)
+       }
+       real_mode_seg = core_real_mode >> 4;
 
        /*
         * 32-bit code.  This is a hack for the moment due to the