[lldb-dev] Is qRegisterInfo required

[Ted Woodward]

Let me second what Greg said here. The Hexagon simulator supports many
different core versions, with different register sets. Having the simulator
implement qRegisterInfo lets LLDB not care which core version it's talking
to. I could look at the target binary, but we can legally run a v4 binary on
a v5 core, so that doesn't work.

I fully expect to be able to use today's LLDB to talk to a hypothetical new
Hexagon core 5 years from now. It won't care about the registers because the
simulator/target stub will tell it what they are.

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-----Original Message-----
From: lldb-dev-bounces at cs.uiuc.edu [mailto:lldb-dev-bounces at cs.uiuc.edu] On
Behalf Of Greg Clayton
Sent: Monday, February 23, 2015 3:36 PM
To: Keno Fischer
Cc: lldb-dev
Subject: Re: [lldb-dev] Is qRegisterInfo required

Not really. We have dealt with changing ARM registers over the years with
iOS and by far the best thing we did was have the "debugserver" binary on
the device tell us what registers are available since it makes things really
simple. If not, we have to get the CPUID from the chip and try to figure out
which generation it was and then figure out what registers were available
with kernel version 1.2.3. So we let the low level software that runs on a
device figure it out as it often has access to sysctl() and many other local
functions that help it to determine what registers are available. Otherwise
you must allow the code on the remote side of this (LLDB) figure it out by
calling down through the GDB remote interface and possibly having to add
packets to return the results of a sysctl() call, or call any other system
functions. It just makes more sense to determine this on the device in the
GDB server since it it always on the device in question.

Greg Clayton