Re: Yet another architecture

[schwidefsky at de dot ibm dot com]

>> 1) The name of the beast. We use the preliminary name s390x at the
moment.
>> I can't say that I like it but I couldn't think of something better. The
>> project name of the machine is "Freeway", the architecture extension is
>> called "esame" and in addition s/390 has been renamed to zSeries. How
>> should we call the configuration name for the 64 bit backend for S/390?
>
>Well, so far we've added 64 to the names.  And 32 the old ones.
>Means, something like
>
>    S/390/64

That was my first thought too but the configuration name would be s39064.
We can't add a hyphen between 390 and 64, can we? I like to have a short
and simple name.

>> 2) How should we integrate this new backend to the glibc? Currently we
have
>> additional "s390x" directories in sysdeps and sysdeps/unix/sysv/linux.
We
>> started with copies from "s390" and modified them.  That differs in
spirit
>> from e.g. sparc who has two subfolders sparc32 and sparc64 in the main
>> sparc directory. Any preferred method?
>
>We should not invent new things.  It's already confusing enough.  I'd
>suggest
>
>- create sysdeps/s390/s390-32
>         sysdeps/s390/s390-64
>
>- move the files which cannot be shared from sysdeps/s390 to
>  sysdeps/390/s390-32
>
>Similarly of course for the Linux specific directory.

Ok, I will do so.

>> 4) I defined a EM_S390X for the 64 bit binaries. Is there a way I could
use
>> EM_S390 plus an additional check for 64 bit in elf_machine_matches_host?
At
>> the moment elf_machine_matches_host only takes one parameter, couldn't
we
>> add the bit size?
>
>I guess you could test for e_machine[EI_CLASS].  I'm not sure what
>problems to expect down the road.  MIPS seems not to have a new EM_*
>constant for their 64-bit architecture but everybody else does.

I would have to modify the prototype for elf_machine_matches_host. This has
an impact on all architectures. Or is there a global array I could use ?

blue skies,
   Martin

Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH
Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247
E-Mail: schwidefsky@de.ibm.com