switch video mode hack by dropping to real mode to call the video bios works!

[bootcensus] / src / boot / boot2.s

diff --git a/src/boot/boot2.s b/src/boot/boot2.s
index 161bd73..37f1026 100644 (file)
--- a/src/boot/boot2.s
+++ b/src/boot/boot2.s
@@ -16,7 +16,7 @@
 
 # this is the second-stage boot loader
        .code16
-       .section .boot2,"a"
+       .section .boot2,"ax"
 
        .set main_load_addr, 0x100000
 
@@ -37,8 +37,8 @@
        # load the whole program into memory starting at 1MB
        call load_main
 
-       mov $0x13, %ax
-       int $0x10
+       #mov $0x13, %ax
+       #int $0x10
 
        # load initial GDT
        lgdt (gdt_lim)
@@ -196,10 +196,11 @@ ldloop:
        push %ecx
        call read_track
 
-       mov buffer, %eax
-       call print_num
-       mov $10, %al
-       call putchar
+       # debug: print the first 32bits of the track
+       #mov buffer, %eax
+       #call print_num
+       #mov $10, %al
+       #call putchar
 
        # copy to high memory
        mov $buffer, %esi
@@ -230,15 +231,15 @@ ldloop:
        mov $10, %ax
        call putchar
 
-       # DBG
-       hlt
-
        ret
 
 rdtrk_msg: .asciz "Reading track: "
 rdcyl_msg: .asciz " - cyl: "
 rdhead_msg: .asciz " head: "
 rdsect_msg: .asciz " start sect: "
+rdlast_msg: .asciz " ... "
+rdok_msg: .asciz "OK\n"
+rdfail_msg: .asciz "failed\n"
 
 read_retries: .short 0
 
@@ -292,8 +293,8 @@ read_try:
        call putstr
        mov trk_sect, %eax
        call print_num
-       mov $10, %al
-       call putchar
+       mov $rdlast_msg, %esi
+       call putstr
 
        # start sector (1-based) in cl[0, 5]
        mov trk_sect, %al
@@ -320,11 +321,13 @@ read_try:
        jmp read_try
 
 read_fail:
+       mov $rdfail_msg, %esi
+       call putstr
        jmp abort_read
 
 read_ok:
-       mov $35, %ax
-       call putchar
+       mov $rdok_msg, %esi
+       call putstr
 
        # reset es to 0 before returning
        xor %ax, %ax
@@ -346,14 +349,15 @@ abort_read:
        jmp 0b
 
 
-
        # better print routines, since we're not constrainted by the 512b of
        # the boot sector.
+       .global cursor_x
+       .global cursor_y
 cursor_x: .long 0
 cursor_y: .long 0
 
 putchar:
-       pusha
+       pushal
        call ser_putchar
 
        cmp $10, %al
@@ -379,7 +383,7 @@ putchar:
        jnz 1f
        call video_newline
 
-1:     popa
+1:     popal
        ret
        
        # expects string pointer in esi
@@ -395,7 +399,7 @@ putstr:
        # expects number in eax
 print_num:
        # save registers
-       pusha
+       pushal
 
        mov $numbuf + 16, %esi
        movb $0, (%esi)
@@ -412,7 +416,7 @@ convloop:
        call putstr
 
        # restore regs
-       popa
+       popal
        ret
 
 
@@ -426,7 +430,7 @@ video_newline:
 0:     ret
 
 scrollup:
-       pusha
+       pushal
        # move 80 * 24 lines from b80a0 -> b8000
        mov $0xb8000, %edi
        mov $0xb80a0, %esi
@@ -437,7 +441,7 @@ scrollup:
        xor %eax, %eax
        mov $40, %ecx
        addr32 rep stosl
-       popa
+       popal
        ret
 
 clearscr:
@@ -549,5 +553,76 @@ kbc_wait_write:
 
 numbuf: .space 16
 
+
+# this is not boot loader code. It's called later on by the main
+# kernel code in 32bit protected mode. It's placed here because
+# it needs to be in base memory as it returns and runs in real mode.
+
+       .code32
+       .align 4
+       # place to save the protected mode IDTR pseudo-descriptor
+       # with sidt, so that it can be restored before returning
+       .short 0
+saved_idtr:
+idtlim:        .short 0
+idtaddr:.long 0
+       # real mode IDTR pseudo-descriptor pointing to the IVT at addr 0
+       .short 0
+rmidt: .short 0x3ff
+       .long 0
+
+       # drop back to unreal mode to set video mode
+       .global set_mode13h
+set_mode13h:
+       pushal
+       cli
+       # save protected mode IDTR and replace it with the real mode vectors
+       sidt (saved_idtr)
+       lidt (rmidt)
+
+       # long jump to load code selector for 16bit code (6)
+       ljmp $0x30,$0f
+0:
+       .code16
+       # disable protection
+       mov %cr0, %eax
+       and $0xfffe, %ax
+       mov %eax, %cr0
+       # load cs <- 0
+       ljmp $0,$0f
+0:     # zero data segments
+       xor %ax, %ax
+       mov %ax, %ds
+       mov %ax, %es
+       mov %ax, %ss
+       nop
+
+       # switch video mode by calling the video bios
+       mov $0x13, %ax
+       int $0x10
+
+       # re-enable protection
+       mov %cr0, %eax
+       or $1, %ax
+       mov %eax, %cr0
+       # long jump to load code selector for 32bit code (1)
+       ljmp $0x8,$0f
+0:
+       .code32
+       # set data selector (2) to all segment regs
+       mov $0x10, %ax
+       mov %ax, %ds
+       mov %ax, %es
+       mov %ax, %ss
+       nop
+
+       # restore 32bit interrupt descriptor table
+       lidt (saved_idtr)
+       sti
+       popal
+       ret
+
+
+       # buffer used by the track loader ... to load tracks.
        .align 16
 buffer: