Changeset b6dfc32 in mainline for kernel/arch/ia32/src/boot/vesa_prot.inc

Timestamp:

2009-03-13T14:44:40Z (15 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

d9167a1c

Parents:

421c833

Message:

support for overriding the preconfigured VESA mode via GRUB command line option

File:

• kernel/arch/ia32/src/boot/vesa_prot.inc (modified) (2 diffs)

kernel/arch/ia32/src/boot/vesa_prot.inc

@@ -1 +1 @@
 #ifdef CONFIG_FB
+
+#define MULTIBOOT_LOADER_MAGIC  0x2BADB002
+#define MBINFO_BIT_CMDLINE      2
+#define MBINFO_OFFSET_CMDLINE   16
+
+        # copy real mode VESA initialization code
+        
         mov $vesa_init, %esi
         mov $VESA_INIT_SEGMENT << 4, %edi
@@ -5 +12 @@
         rep movsb
         
+        # check for GRUB command line
+        
+        mov grub_eax, %eax
+        cmp $MULTIBOOT_LOADER_MAGIC, %eax
+        jne no_cmdline
+        
+        mov grub_ebx, %ebx
+        mov (%ebx), %eax
+        bt $MBINFO_BIT_CMDLINE, %eax
+        jnc no_cmdline
+        
+        # skip the kernel path in command line
+        
+        mov MBINFO_OFFSET_CMDLINE(%ebx), %esi
+        
+        skip_loop:
+                lodsb
+                
+                cmp $0, %al
+                je no_cmdline
+                
+                cmp $' ', %al
+                je skip_loop_done
+                
+                jmp skip_loop
+        skip_loop_done:
+        
+        mov (%esi), %al
+        cmp $0, %al
+        je no_cmdline
+        
+        # copy at most 23 characters from command line
+        
+        mov $VESA_INIT_SEGMENT << 4, %edi
+        add $default_mode - vesa_init, %edi
+        mov $23, %ecx
+        
+        cmd_loop:
+                lodsb
+                stosb
+                
+                cmp $0, %al
+                je cmd_loop_done
+                
+                loop cmd_loop
+        cmd_loop_done:
+        
+        # zero termination
+        
+        xor %eax, %eax
+        stosb
+        
+        no_cmdline:
+        
+        # jump to the real mode
+        
         mov $VESA_INIT_SEGMENT << 4, %edi
         jmpl *%edi
         
         vesa_meeting_point:
+                # returned back to protected mode
+                
                 mov %esi, KA2PA(vesa_ph_addr)
                 mov %di, KA2PA(vesa_height)