core: make the COMBOOT API available to in-kernel PM code

Make it possible to call the COMBOOT API from in-kernel PM code,
simply by setting up the COMBOOT API earlier and only tearing it down
during final shutdown.

WARNING: the COMBOOT API is quite possibly probably not reentrant; I
haven't checked it...

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

4 files changed, 31 insertions, 21 deletions

diff --git a/core/cleanup.inc b/core/cleanup.inc
index 9166f011..7db5593d 100644
--- a/core/cleanup.inc
+++ b/core/cleanup.inc
@@ -50,5 +50,7 @@ cleanup_hardware:
 .no_vmware:
 %endif
 
+		call comboot_cleanup_api
+
 		popad
 		ret
diff --git a/core/comboot.inc b/core/comboot.inc
index 7d9efba2..b1048bb5 100644
--- a/core/comboot.inc
+++ b/core/comboot.inc
@@ -148,8 +148,8 @@ comboot_return:	cli			; Don't trust anyone
 		jmp comboot_exit
 
 ;
-; Set up the COMBOOT API interrupt vectors.  This is also used
-; by the COM32 code.
+; Set up the COMBOOT API interrupt vectors.  This is now done at
+; initialization time.
 ;
 comboot_setup_api:
 		mov di,DOSErrTramp	; Error trampolines
@@ -178,6 +178,18 @@ comboot_setup_api:
 		loop .loop2
 		ret
 
+;
+; Restore the original state of the COMBOOT API vectors
+;
+comboot_cleanup_api:
+		pusha
+		mov si,DOSSaveVectors
+		mov di,4*20h
+		mov cx,20h
+		rep movsd		; Restore DOS-range vectors
+		popa
+		ret
+
 		section .bss16
 		alignb 4
 DOSSaveVectors	resd 32
@@ -296,12 +308,6 @@ comboot_exit_msg:
 		pop bx			; Return address
 		RESET_STACK_AND_SEGS SI	; Contains cld
 		call adjust_screen	; The COMBOOT program might have changed the screen
-		pusha
-		mov si,DOSSaveVectors
-		mov di,4*20h
-		mov cx,20h
-		rep movsd		; Restore DOS-range vectors
-		popa
 		jcxz .nomsg
 		mov si,KernelCName
 		call writestr
diff --git a/core/hello.c b/core/hello.c
index c4b28032..6c12c738 100644
--- a/core/hello.c
+++ b/core/hello.c
@@ -3,18 +3,14 @@
 
 void myputchar(int c)
 {
-#if 1
   static com32sys_t ireg;
+  static uint16_t *vram = 0xb8000;
 
-  ireg.eax.b[1] = 0x0e;
-  ireg.eax.b[0] = c;
-  ireg.ebx.w[0] = 0x0007;
-  core_intcall(0x10, &ireg, NULL);
-#else
-  static uint16_t *vram = (void *)0xb8000;
+  ireg.eax.b[1] = 0x02;
+  ireg.edx.b[0] = c;
+  core_intcall(0x21, &ireg, NULL);
 
-  *vram++ = (uint8_t)c + 0x1f00;
-#endif
+  *vram++ = c + 0x1f00;
 }
 
 void myputs(const char *str)
diff --git a/core/init.inc b/core/init.inc
index 90c607ee..7f65ffa6 100644
--- a/core/init.inc
+++ b/core/init.inc
@@ -43,9 +43,6 @@ common_init:
 		mov cx,__uibss_dwords
 		rep stosd
 
-		; Now set up screen parameters
-		call adjust_screen
-
 ;
 ; Initialize configuration information
 ;
@@ -63,4 +60,13 @@ common_init:
 		add ax,PKTBUF_SIZE
 		loop .setbufptr
 %endif
-		section .text16			; This is an inline file...
+
+;
+; Set up the COMBOOT APIs
+;
+		call comboot_setup_api
+
+;
+; Now set up screen parameters
+;
+		call adjust_screen