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Date: Mon, 22 Feb 2010 15:01:00 -0000
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From: Mark Kettenis <mark.kettenis@xs4all.nl>
To: hjl.tools@gmail.com
CC: gdb-patches@sourceware.org
In-reply-to: <6dc9ffc81002220617o1d348e68hc918d434118cadcb@mail.gmail.com> 	(hjl.tools@gmail.com)
Subject: Re: PATCH: Enable x86 XML target descriptions
References: <20100210200303.GA19632@lucon.org> 	 <20100218054312.GA9022@lucon.org> <20100218153402.GA27929@lucon.org> 	 <20100218230135.GA17916@intel.com> 	 <201002221342.o1MDgSZA029705@glazunov.sibelius.xs4all.nl> <6dc9ffc81002220617o1d348e68hc918d434118cadcb@mail.gmail.com>
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> Date: Mon, 22 Feb 2010 06:17:29 -0800
> From: "H.J. Lu" <hjl.tools@gmail.com>
>
> >> +/* Get Linux/x86 target description from running target.  */
> >> +
> >> +static const struct target_desc *
> >> +amd64_linux_read_description (struct target_ops *ops)
> >> +{
> >> +  if (gdbarch_ptr_bit (target_gdbarch) == 64)
> >> +    return tdesc_amd64_linux;
> >> +  else
> >> +    return tdesc_i386_linux;
> >> +}
> >> +
> >
> > This made me wonder what happens if you attach to a process without
> > loading an executable first.  Currently this works, since GDB can
> > figure out what executable belongs to the the process and load the
> > executable automatically.  But I fear a chicken & egg problem here:
> > the gdbarch is derviced from the tdesc, but in order to determine the
> > tdesc you need a gdbarch.
> 
> How do you attach to a process without loading an executable first?
> Gdb has to load something to debug. Do you have a testcase? I will
> fix it if it doesn't work already.

$ gdb
...
(gdb) attach PID