[Lldb-commits] [PATCH] D16853: Use BKPT instead of UDF for arm/thumb breakpoints

Tamas Berghammer via lldb-commits lldb-commits at lists.llvm.org
Tue Feb 9 05:36:53 PST 2016

tberghammer added a comment.

In http://reviews.llvm.org/D16853#347120, @omjavaid wrote:

> GDB doesnt use bkpt instruction for user debugging for the reason that it interferes with jtag debug probes. I am not sure if LLDB will be ever used with a jtag probe in near future but still a jtag prob might be connected to the same hardware which is using LLDB to debug a user space application.

The change is restricted to Linux and I am pretty sure that if somebody want to do jtag debugging with LLDB then he/she have to implement a new platform module. If a separate jtag probe is connected to the hardware then it might cause an issue but I don't think we have any user who is doing it (why would you use 2 debugging at the same time?)

> heres a discussion which happened some years back on similar issues:


> https://sourceware.org/ml/gdb-patches/2010-01/msg00624.html


> http://www.spinics.net/lists/arm-kernel/msg80476.html

If we hit the issues they are mentioning with using the BKPT instruction then we have to implement some workarounds for it but as they describe they are not perfect so I would rather avoid them.

> I am fine with using bkpt as long as it helps us debug IT blocks and doesnt interfere with any of our currently functionality.

I run the test suit and nothing showed up so I think we are mostly safe in this side.


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