Re: PDP-10 port

[Andreas Jaeger]

Lars Brinkhoff <address@hidden> writes:

> Andreas Jaeger <address@hidden> writes:
>> Lars Brinkhoff <address@hidden> writes:
>> > I will probably soon start working on porting glibc to the PDP-10
>> > architecture running the TOPS-20 operating system.
>> That looks like fun, I fear you need to put quite some work into it.
>
> Yes, that's expected.
>
> Do you (or anyone else) know to what extent the necessary
> modifications could be accepted back into GNU libc?  To give an idea
> of the obstacles to overcome:
>
> * The PDP-10 is word-addressed, so there are very strict alignment
>   requirements.

That shouldn't be a problem.

> * The word size is 36 bits, so int is 36, short 18, and char 9 bits.
>   (Support for 8/16/32-bit types in the GCC port may help with this.)

I fear that this is a major problem.

>
> * The Linux/VAX people reports that the library expect IEEE floating
>   point types, which are not supported in hardware on the PDP-10.

glibc has a Softfloating point library in soft-fp that needs to be
adjusted.

>
> Finally, anything in particular I should do to prepare myself for the
> port?  Any mailing lists subscriptions recommended?  I have browsed
> through the manual and the FAQ.

Subscribe to libc-alpha and try to understand the sysdeps directory.

If you like to get your contributions into glibc, we need a copyright
assigment.

Andreas
-- 
 Andreas Jaeger
  SuSE Labs address@hidden
   private address@hidden
    http://www.suse.de/~aj