[Qemu-devel] [patch] Remove requirement for -hda with -kernel

[Ross Kendall Axe]

The requirement to provide an -hda argument when doing a direct boot of
a linux kernel has irritated me for some time.  This patch removes that
requirement by creating a temporary 1 sector hda as needed.

Ross

Index: hw/pc.c
===================================================================
RCS file: /cvsroot/qemu/qemu/hw/pc.c,v
retrieving revision 1.35
diff -u -p -r1.35 pc.c
--- hw/pc.c     15 Jan 2005 12:02:56 -0000      1.35
+++ hw/pc.c     27 Apr 2005 02:29:20 -0000
@@ -446,8 +446,26 @@ void pc_init(int ram_size, int vga_ram_s
         uint8_t old_bootsect[512];
 
         if (bs_table[0] == NULL) {
-            fprintf(stderr, "A disk image must be given for 'hda' when booting 
a Linux kernel\n");
-            exit(1);
+            char template[] = "/tmp/qemu.XXXXXX";
+            int tmpfile = mkstemp(template);
+
+            fprintf(stderr, "qemu: Disk image not given for 'hda' when booting"
+                    " a Linux kernel; inventing one\n");
+            if(tmpfile == -1) {
+                fprintf(stderr, "qemu: couldn't create temporary diskimage\n");
+                exit(1);
+            }
+            lseek(tmpfile, 511, SEEK_SET);
+            write(tmpfile, "", 1);
+            bs_table[0] = bdrv_new("hda");
+            if (bdrv_open(bs_table[0], template, snapshot) < 0) {
+                fprintf(stderr, "qemu: could not load temporary diskimage 
'%s'\n",
+                        template);
+                exit(1);
+            }
+            close(tmpfile);
+            unlink(template);
+            boot_device = 'c';
         }
         snprintf(buf, sizeof(buf), "%s/%s", bios_dir, LINUX_BOOT_FILENAME);
         ret = load_image(buf, bootsect);

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