Patchwork Re: pc-bios/bios.bin - where it comes from?

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Submitter Gerd Hoffmann
Date March 5, 2010, 12:40 p.m.
Message ID <4B90FBC3.4000700@redhat.com>
Download mbox | patch
Permalink /patch/47005/
State New
Headers show

Comments

Gerd Hoffmann - March 5, 2010, 12:40 p.m.
Hi,

>> BTW, is there any reason preventing updating vgabios
>> to 0.6c version - the latest released one?

Yes.  It expects some new bochs vbe interface bits being present.  qemu 
doesn't provide them (yet), thus it simply doesn't work.

> There's no compelling improvement in 0.6c and updating vgabios is not
> something I'm eager to do unless there's a strong justification.

Oh, there is one noticable improvement (patch attached, cherry-picked 
from vgabios cvs).  vgabios can pick the lfb address from pci config 
space now.  This in turn allows us to kill the lfb mapping at hardcoded 
address 0xe0000000 (except for isapc).

cheers,
   Gerd
From 31740228eccdb2b3f96d9f9ce1d65f947d2b744b Mon Sep 17 00:00:00 2001
Subject: use VBE LFB address from PCI base address if present

Make vgabios lookup the lfb address in pci config space instead
of using the hard-coded address 0xe0000000.

Patch

diff --git a/clext.c b/clext.c
index c7a2ad0..b0b6834 100644
--- a/clext.c
+++ b/clext.c
@@ -948,7 +948,8 @@  cirrus_vesa_01h_3:
   ;; 32-bit LFB address
   xor ax, ax
   stosw
-  call cirrus_get_lfb_addr
+  mov ax, #0x1013 ;; vendor Cirrus
+  call _pci_get_lfb_addr
   stosw
   or ax, ax
   jz cirrus_vesa_01h_4
@@ -1293,54 +1294,6 @@  cgm_2:
 cgm_3:
   ret
 
-  ; get LFB address
-  ; out - ax:LFB address (high 16 bit)
-  ;; NOTE - may be called in protected mode
-cirrus_get_lfb_addr:
-  push cx
-  push dx
-  push eax
-    xor cx, cx
-    mov dl, #0x00
-    call cirrus_pci_read
-    cmp ax, #0xffff
-    jz cirrus_get_lfb_addr_5
- cirrus_get_lfb_addr_3:
-    mov dl, #0x00
-    call cirrus_pci_read
-    cmp ax, #0x1013 ;; cirrus
-    jz cirrus_get_lfb_addr_4
-    add cx, #0x8
-    cmp cx, #0x200 ;; search bus #0 and #1
-    jb cirrus_get_lfb_addr_3
- cirrus_get_lfb_addr_5:
-    xor dx, dx ;; no LFB
-    jmp cirrus_get_lfb_addr_6
- cirrus_get_lfb_addr_4:
-    mov dl, #0x10 ;; I/O space #0
-    call cirrus_pci_read
-    test ax, #0xfff1
-    jnz cirrus_get_lfb_addr_5
-    shr eax, #16
-    mov dx, ax ;; LFB address
- cirrus_get_lfb_addr_6:
-  pop eax
-  mov ax, dx
-  pop dx
-  pop cx
-  ret
-
-cirrus_pci_read:
-  mov eax, #0x00800000
-  mov ax, cx
-  shl eax, #8
-  mov al, dl
-  mov dx, #0xcf8
-  out dx, eax
-  add dl, #4
-  in  eax, dx
-  ret
-
 ;; out - al:bytes per pixel
 cirrus_get_bpp_bytes:
   push dx
diff --git a/vbe.c b/vbe.c
index 87f7414..8af5255 100644
--- a/vbe.c
+++ b/vbe.c
@@ -888,32 +888,37 @@  Bit16u *AX;Bit16u CX; Bit16u ES;Bit16u DI;
         ModeInfoBlock     info;
         ModeInfoListItem  *cur_info;
         Boolean           using_lfb;
+        Bit16u            lfb_addr;
 
 #ifdef DEBUG
         printf("VBE vbe_biosfn_return_mode_information ES%x DI%x CX%x\n",ES,DI,CX);
 #endif
 
         using_lfb=((CX & VBE_MODE_LINEAR_FRAME_BUFFER) == VBE_MODE_LINEAR_FRAME_BUFFER);
-        
+
         CX = (CX & 0x1ff);
-        
+
         cur_info = mode_info_find_mode(CX, using_lfb, &cur_info);
 
         if (cur_info != 0)
         {
 #ifdef DEBUG
                 printf("VBE found mode %x\n",CX);
-#endif        
+#endif
                 memsetb(ss, &info, 0, sizeof(ModeInfoBlock));
                 memcpyb(ss, &info, 0xc000, &(cur_info->info), sizeof(ModeInfoBlockCompact));
                 if (using_lfb) {
                   info.NumberOfBanks = 1;
                 }
+                lfb_addr = pci_get_lfb_addr(0x1234); // experimental vendor
+                if (lfb_addr > 0) {
+                  info.PhysBasePtr = ((Bit32u)lfb_addr << 16);
+                }
                 if (info.WinAAttributes & VBE_WINDOW_ATTRIBUTE_RELOCATABLE) {
                   info.WinFuncPtr = 0xC0000000UL;
                   *(Bit16u *)&(info.WinFuncPtr) = (Bit16u)(dispi_set_bank_farcall);
                 }
-                
+
                 result = 0x4f;
         }
         else
diff --git a/vgabios.c b/vgabios.c
index 3fd9f2f..1738b47 100644
--- a/vgabios.c
+++ b/vgabios.c
@@ -3830,6 +3830,64 @@  void printf(s)
 }
 #endif
 
+ASM_START
+  ; get LFB address from PCI
+  ; in - ax: PCI device vendor
+  ; out - ax: LFB address (high 16 bit)
+  ;; NOTE - may be called in protected mode
+_pci_get_lfb_addr:
+  push bx
+  push cx
+  push dx
+  push eax
+    mov bx, ax
+    xor cx, cx
+    mov dl, #0x00
+    call pci_read_reg
+    cmp ax, #0xffff
+    jz pci_get_lfb_addr_5
+ pci_get_lfb_addr_3:
+    mov dl, #0x00
+    call pci_read_reg
+    cmp ax, bx ;; check vendor
+    jz pci_get_lfb_addr_4
+    add cx, #0x8
+    cmp cx, #0x200 ;; search bus #0 and #1
+    jb pci_get_lfb_addr_3
+ pci_get_lfb_addr_5:
+    xor dx, dx ;; no LFB
+    jmp pci_get_lfb_addr_6
+ pci_get_lfb_addr_4:
+    mov dl, #0x10 ;; I/O space #0
+    call pci_read_reg
+    test ax, #0xfff1
+    jnz pci_get_lfb_addr_5
+    shr eax, #16
+    mov dx, ax ;; LFB address
+ pci_get_lfb_addr_6:
+  pop eax
+  mov ax, dx
+  pop dx
+  pop cx
+  pop bx
+  ret
+
+  ; read PCI register
+  ; in - cx: device/function
+  ; in - dl: register
+  ; out - eax: value
+pci_read_reg:
+  mov eax, #0x00800000
+  mov ax, cx
+  shl eax, #8
+  mov al, dl
+  mov dx, #0xcf8
+  out dx, eax
+  add dl, #4
+  in  eax, dx
+  ret
+ASM_END
+
 #ifdef VBE
 #include "vbe.c"
 #endif