Re: New target porting time estimates?

[Richard Tierney <mfoc73 at dsl dot pipex dot com>]

Ian Lance Taylor wrote:

> If the processor is just like other processors, then why bother
> building it--

Exactly. I'm afraid it's different in weird and wonderful (and, 
currently, unknown) ways. I need to get the most out of the new DFA 
scheduler, for starters.

> Second, how familiar is the person or people doing the port with
> working on gcc, and how much experience do they have developing new
> ports?

Not at all/None. Can there be more than 50 people in the whole world 
who've done a working gcc port? I've read Hans-Peter Nilsson's stuff, 
I'm working through Richard Kenner's docs, and I've had a first look at 
the porting guide (there's nothing similar for binutils, though), and I 
still don't know enough to start. It also seems to me that just finding 
good documentation on RTL may be harder than rewriting it from scratch. 
Does anyone have any RTL doc pointers?

> I think that when I was at Cygnus, we usually figured that one
> experienced programmer could do a complete gcc and binutils port for a
> fairly typical processor in three to four months.  This would be a
> person who had already done extensive work on gcc and the binutils,
> and who was working next to and had immediate access to most of the
> top experts on the gcc and binutils code.
>
> On the other hand, if we are talking about a non-expert programmer,
> with no experience on gcc and the binutils, relying on the public
> mailing lists for help, I think it would take a good dose of luck and
> perseverance for the port to ever be finished at all.

Thanks. I think I'll estimate 9 months, followed by a lifetime of 
maintenance. The only other estimate I found on the web was Tim Olson's 
statement that "A simple basic port (without working out all the subtle 
bugs) can be done in a man-month or so." H-PN doesn't seem to give any 
estimates - he still seems to be working on it..   :)

> I think I'm telling it like it is, but I should also reveal my bias by
> saying that my employer, Wasabi Systems, will do this type of work for
> pay.  There are several other companies and consultants, well
> represented on these mailing lists, which you can also hire for this
> type of work.

Thanks again, but I'm afraid that this one has to be done in-house.

Cheers

RT