Re: [Qemu-devel] [PATCH] set vidmode in linux kernel header when boot x86 using qemu bootloader

[joy zhao <yanhwizhao@gmail.com>]

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hi Anthony,
This is my  updated version of patch. I've been using strtoul to translate
string. I do not  have get_vga_mode() return vga_mode directly because I do
not want to leave the default value of vga_mode  to be decided by qemu,
but by kernel when no "vga=..." is specified.

B.R.
Joy

Signed-off-by: Joy Zhao <yanhwizhao@gmail.com>

diff --git a/qemu/hw/pc.c b/qemu-new/hw/pc.c
index 66cc780..dc1c20f 100644
--- a/qemu/hw/pc.c
+++ b/qemu-new/hw/pc.c
@@ -36,6 +36,7 @@
 #include "hpet_emul.h"
 #include "watchdog.h"
 #include "smbios.h"
+#include <stdlib.h>

 /* output Bochs bios info messages */
 //#define DEBUG_BIOS
@@ -593,6 +594,41 @@ static long get_file_size(FILE *f)
     return size;
 }

+static int get_vga_mode(const char* kernel_cmdline, uint16_t *vga_mode)
+{
+    char mode[10];
+    int i = 0;
+    char *p = strstr(kernel_cmdline, "vga=");
+    if(p == NULL)
+        return 1;
+
+    p += 4;
+
+    while(*p != ' ' && *p != '\0' && i < 9) {
+        mode[i] = *p;
+        i++;
+        p++;
+    }
+    mode[i] = '\0';
+
+    if(!strncmp(mode, "ask", 3))
+        *vga_mode = 0xfffd;
+    else if(!strncmp(mode, "normal",6))
+        *vga_mode = 0xffff;
+    else if(!strncmp(mode, "ext", 3))
+        *vga_mode = 0xfffe;
+    else{
+        errno = 0;
+        *vga_mode = strtoul(mode, NULL, 0);
+        if(errno){
+            fprintf(stderr, "vga mode Overflow or unsupported base
value\n");
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
 static void load_linux(target_phys_addr_t option_rom,
                        const char *kernel_filename,
          const char *initrd_filename,
@@ -605,6 +641,7 @@ static void load_linux(target_phys_addr_t option_rom,
     uint16_t real_seg;
     int setup_size, kernel_size, initrd_size, cmdline_size;
     uint32_t initrd_max;
+    uint16_t vid_mode;
     uint8_t header[1024];
     target_phys_addr_t real_addr, prot_addr, cmdline_addr, initrd_addr;
     FILE *f, *fi;
@@ -683,6 +720,10 @@ static void load_linux(target_phys_addr_t option_rom,
     if (protocol >= 0x200)
  header[0x210] = 0xB0;

+    /*parse cmdline and set vga mode*/
+    if(!get_vga_mode(kernel_cmdline, &vid_mode))
+        stw_p(header+0x1fa, vid_mode);
+
     /* heap */
     if (protocol >= 0x201) {
  header[0x211] |= 0x80; /* CAN_USE_HEAP */

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