[syslinux:pathbased] core: let xfer_buf_seg, real_mode_seg be assigned by the linker
syslinux-bot for H. Peter Anvin
hpa at zytor.com
Sun Feb 21 16:09:19 PST 2010
Commit-ID: ced4ec389bd2d915f3e00e41736737279fba89ec
Gitweb: http://syslinux.zytor.com/commit/ced4ec389bd2d915f3e00e41736737279fba89ec
Author: H. Peter Anvin <hpa at zytor.com>
AuthorDate: Sun, 21 Feb 2010 15:42:03 -0800
Committer: H. Peter Anvin <hpa at zytor.com>
CommitDate: Sun, 21 Feb 2010 15:42:03 -0800
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 at zytor.com>
---
core/com32.inc | 2 +-
core/conio.inc | 2 +-
core/init.inc | 16 ++++++++++++----
core/isolinux.asm | 2 +-
core/kernel.inc | 2 +-
core/layout.inc | 25 +++++++++++++++++--------
core/loadhigh.inc | 2 +-
core/runkernel.inc | 6 +++---
core/syslinux.ld | 15 +++++++++++++--
9 files changed, 50 insertions(+), 22 deletions(-)
diff --git a/core/com32.inc b/core/com32.inc
index 3fa2d31..b198dac 100644
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
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