Re: [PATCH v3 2/6] x86/debugger: separate Xen and guest debugging debugger_trap_* functions

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/08/2021 13:16, Jan Beulich wrote:
> On 18.08.2021 22:29, Bobby Eshleman wrote:
>> Unlike debugger_trap_fatal() and debugger_trap_immediate(),
>> debugger_trap_entry() is specific to guest debugging and *NOT* the
>> debugging of Xen itself. That is, it is part of gdbsx functionality and
>> not the Xen gdstub. This is evidenced by debugger_trap_fatal()'s usage
>> of domain_pause_for_debugger(). Because of this, debugger_trap_entry()
>> does not belong alongside the generic Xen debugger functionality.
> I'm not convinced this is what the original intentions were. Instead I
> think this was meant to be a generic hook function which initially
> only cared to deal with the gdbsx needs.

It doesn't exactly matter what the original intentions where - what we
currently have is unused and and a clear source of confusion between two
unrelated subsystems.

It is unclear that the gdbstub is even usable, given at least a decade
of bitrot.

Keeping an empty static inline in the enabled case is nonsense, because
at the point you need to edit Xen to insert some real debugging, there
are better ways to do it in something which isn't even a catch-all
despite appearing to be one.

~Andrew