Re: [Qemu-devel] [SeaBIOS PATCH v2] boot: support strict boot and make it configurable

[Kevin O'Connor <kevin@koconnor.net>]

On Wed, Dec 26, 2012 at 08:55:40AM +0800, Amos Kong wrote:
> Current seabios will try to boot from selected devices first,
> if they are all failed, seabios will also try to boot from
> un-selected devices.
> 
> For example:
> @ qemu-kvm -boot order=n,menu=on ...
> 
> Guest will boot from network first, if it's failed, guest will try to
> boot from other un-selected devices (floppy, cdrom, disk) one by one.
> 
> We need to make it configurable, seabios user can config it by a rom
> file('etc/boot-strict'). 'strict boot' means only boot from user
> selected devices.
> 
> I added some comments in this patch to explain why we can judge if
> device is selected or not by DEFAULT_PRIO(9999). I also added 'selected'
> flag in struct bootentry_s and struct bev_s to make it clearer.
> 
> If this patch is accepted, I will add a boot option (-boot strict=on)
> for qemu.

I think it would be simpler to use the existing bootorder file instead
of introducing a new "boot-strict" file.  Something like the below
(untested).

-Kevin


diff --git a/src/boot.c b/src/boot.c
index c67cc7f..56843e3 100644
--- a/src/boot.c
+++ b/src/boot.c
@@ -291,6 +291,7 @@ static struct bootentry_s *BootList;
 #define IPL_TYPE_CBFS        0x20
 #define IPL_TYPE_BEV         0x80
 #define IPL_TYPE_BCV         0x81
+#define IPL_TYPE_HALT        0xf0
 
 static void
 bootentry_add(int type, int prio, u32 data, const char *desc)
@@ -488,6 +489,10 @@ boot_prep(void)
     interactive_bootmenu();
     wait_threads();
 
+    int haltprio = find_prio("HALT");
+    if (haltprio >= 0)
+        bootentry_add(IPL_TYPE_HALT, haltprio, 0, "HALT");
+
     // Map drives and populate BEV list
     struct bootentry_s *pos = BootList;
     while (pos) {
@@ -672,6 +677,9 @@ do_boot(int seq_nr)
     case IPL_TYPE_BEV:
         boot_rom(ie->vector);
         break;
+    case IPL_TYPE_HALT:
+        boot_fail();
+        break;
     }
 
     // Boot failed: invoke the boot recovery function