[avr-gcc-list] Re: Any SimulAVR or avrtest users out there?

[Paulo Marques]

Weddington, Eric wrote:
> Hi All,

Hi, Eric

> There's a lot of new work being done at the SimulAVR project: 
> <http://savannah.nongnu.org/projects/simulavr>
> 
> Specifically the "old" simulavr project hasn't had much maintenance
> done on it in years. There is an "avrtest" project (hosted at WinAVR)
> that is used exclusively as a simulator for the GCC Regression Test
> Suite. The newer, C++ based simulavrxx is being worked on heavily, with
> the intent that it will supersede both the old simulavr and avrtest and
> include as much functionality from both as possible.
> 
> We would like to turn the simulavrxx branch into a best-of-class AVR
> simulator that will work for all of the use cases, on all platforms that
> the AVR toolchain is used on, so we don't have various project forks
> that don't work effectively for all. At some point we would like for the
> old simulavr and avrtest to go away and to be able to use the C++ based
> simulavr for everything.

I understand the reasons to want this, but I believe the initial
premises for the avrtest development still apply: it is very hard to do
a full-featured simulator (with complete peripheral emulation,
gdb-server, etc.) that runs gcc regression tests as fast as possible.

IIRC, in the latest benchmarks I did with avrtest, it performed as fast
as a 100Mhz AVR on a 2.8GHz pentium 4.

The problem with the regression tests, is that when a test fails and is
stuck in a infinite loop (or similar) it takes a long time to execute
enough instructions to be confident that the test is actually stuck and
not just taking a long time to complete.

Most tests ran in fractions of a second, but when this happened it could
take a few minutes to fail the test, and this represented a big slice of
the total time to run the regression suite.

I think that the effort of making simulavrxx configurable enough to work
as a full-featured simulator or a "regression test fast executer" is
actually larger than the maintenance required to keep avrtest working
with new architectures. Although I do realize that my opinion might be a
little biased here ;)

-- 
Paulo Marques
Software Development Department - Grupo PIE, S.A.
Phone: +351 252 290600, Fax: +351 252 290601
Web: www.grupopie.com

"Who is general Failure and why is he reading my disk?"