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Re: [Xen-devel] possible changes was Re: [PATCH] make domu_debug run-time option + fix int3 handling for MP

> Doesn't the gdb server have to attach to the new vm to be able to set 
> the breakpoint, leading to a race anyway? Or have you some way to 
> pre-insert an int3?

There have been times when I've messed things up really early on so I've just 
re-compiled with an int3 in locore.s. For developers who wan't to be able to 
breakpoints early in boot, I've added a boot time option to the command line 
that gets handled in machdep.c:

        if ((caddr_t)xen_start_info->cmd_line)
                kern_envp = xen_setbootenv((caddr_t)xen_start_info->cmd_line);

        boothowto |= xen_boothowto(kern_envp);

        if (boothowto & RB_GDB_PAUSE)
            __asm__("int $0x3;");

This way the VM got paused very early on in boot so that when the gdbserver got 
to attaching to it it hadn't gotten very far.


But my recent jaunt through xm has lead me to a cleaner solution:

gopts.opt('paused', short='p',
          fn=set_true, default=0,
          use='Leave the domain paused after it is created.')

So I think we're good.



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