Re: [Qemu-devel] Re: [PATCH v5 18/18] gdbstub: x86: Switch 64/32 bit registers dynamically

[Paul Brook]

> > In the absence of real information gdb falls back to the current CPU
> > mode, which is a bit in the CPU status register. Exactly which
> > register/bit depends whether you're talking to an M-profile device.
> > M-profile cores are identified based on the XML register descriptions. If
> > you don't have an XML capable target then you don't get to debug
> > M-profile devices.
>
> ...and this surely doesn't map on x86 (yet): gdb has no clue at all
> about the CPU mode as it has no clue about segments or control registers.
>
> > IIRC There's also a gdb option to override the fallback mode.
>
> For x86, the core of the issue is a decoupled control of the gdb remote
> protocol and the disassembly mode. I guess I have to dig a bit in the
> code to see if the hard coupling we see in practice can be broken up.
> Not according to the command help I found so far.

This is sounding a lot like "we can't be bothered fixing gdb, so we're going 
to add ugly hacks to qemu instead". I don't find this a particularly 
convincing argument.

Paul