Hi Vineet, On Thu, 2018-01-18 at 10:54 -0800, Vineet Gupta wrote: > On 01/18/2018 05:48 AM, Alexey Brodkin wrote: > > HS48 core starts with dual-issue enabled but in some cases like > > debugging as well as benchmarking it might be useful to disable > > dual-issue for a particular run. > > > > Note: > > 1. To disable dual-issue user has to change a value of a global variable > > in target's memory right before start of Linu kernel execution > > (most probably via JTAG) > > > > 2. Disabling happens very early on boot and to get it back enabled it's > > required to restart Linux kernel. I.e. with this change we don't allow > > toggling dual-issue state in random moments of run-time > > But we need access to a debugger anyways to change this global variable. > If you already have that won't it be better to change the aux register itself from > the debugger itself. > I don't really see how the global variable way of toggle adds any value here ? I think there's some sense in a global variable. 1. Not sure if OpenOCD/GDB pair for ARC allows to read/write random AUX regs. Probably allows but I guess we'll need a new .xml description which lists EXEC_CTRL AUX reg. Correct me if I'm wrong here. 2. If somebody wants to disable dual-issue persistently (here I mean building an image which had dual-issue disabled and there's no need to alter anything after image loading) then it's possible just to change a simple and very obvious line in arch/arc/kernel/setup.c other than trying to guess what could be good place in sources to stick that AUX reg write. Note we don't explicitly do reads of AUX_EXEC_CTRL instead we just use READ_BCR macro so for newcomers it might not be immediately obvious what to do and where. Add the fact that logic of the flag is reversed... -Alexey
