Discussion:
I query about quality of SuperH-port of newlib
Johann-Tobias Schäg
2018-10-17 18:47:32 UTC
Permalink
Hello,

I am looking for a demonstration idea for the "new" J-Core cpu architecture which is actually just open source implementation of a slightly modified SuperH (whose patents expired).
I was thinking about porting eLua which depends on newlib.
What SH versions do you support? 
(SH1, SH2, SH3, SH4, SH2a)
If not what would be necessary to port it to J2 (being SH2 + new atomic CAS Instruction + back ported shift instructions from SH3)
Does newlib depend on features which require an mmu?
Israel Jacquez
2018-10-17 18:52:51 UTC
Permalink
Post by Johann-Tobias Schäg
Hello,
I am looking for a demonstration idea for the "new" J-Core cpu
architecture which is actually just open source implementation of a
slightly modified SuperH (whose patents expired).
I was thinking about porting eLua which depends on newlib.
What SH versions do you support?
(SH1, SH2, SH3, SH4, SH2a)
I've been able to use Newlib just fine on SH-2 (Sega Saturn, no MMU).
Though, 90% of the functionality from Newlib is beyond the scope of the
hardware.
Post by Johann-Tobias Schäg
If not what would be necessary to port it to J2 (being SH2 + new atomic
CAS Instruction + back ported shift instructions from SH3)
Does newlib depend on features which require an mmu?
Please correct me if I'm wrong, but there's a way to override syscalls,
specifically *sbrk()?

Sincerely Johann-Tobias Schäg
Dave Nadler
2018-10-17 18:59:17 UTC
Permalink
Post by Israel Jacquez
Post by Johann-Tobias Schäg
Hello,
I am looking for a demonstration idea for the "new" J-Core cpu
architecture which is actually just open source implementation of a
slightly modified SuperH (whose patents expired).
I was thinking about porting eLua which depends on newlib.
What SH versions do you support?
(SH1, SH2, SH3, SH4, SH2a)
I've been able to use Newlib just fine on SH-2 (Sega Saturn, no MMU).
Though, 90% of the functionality from Newlib is beyond the scope of the
hardware.
Post by Johann-Tobias Schäg
If not what would be necessary to port it to J2 (being SH2 + new atomic
CAS Instruction + back ported shift instructions from SH3)
Does newlib depend on features which require an mmu?
Please correct me if I'm wrong, but there's a way to override syscalls,
specifically *sbrk()?
Implement sbrk as appropriate for your memory layout, see:
https://www.embecosm.com/appnotes/ean9/ean9-howto-newlib-1.0.html
Post by Israel Jacquez
Sincerely Johann-Tobias Schäg
--
Dave Nadler, USA East Coast voice (978) 263-0097, ***@nadler.com, Skype
Dave.Nadler1
Joel Sherrill
2018-10-17 19:14:44 UTC
Permalink
Another option is to use RTEMS and have a free RTOS with more
functionality. We have supported the SH for many years.

--joel
Post by Dave Nadler
On Wed, Oct 17, 2018 at 11:47 AM Johann-Tobias Schäg <
Post by Johann-Tobias Schäg
Hello,
I am looking for a demonstration idea for the "new" J-Core cpu
architecture which is actually just open source implementation of a
slightly modified SuperH (whose patents expired).
I was thinking about porting eLua which depends on newlib.
What SH versions do you support?
(SH1, SH2, SH3, SH4, SH2a)
I've been able to use Newlib just fine on SH-2 (Sega Saturn, no MMU).
Though, 90% of the functionality from Newlib is beyond the scope of the
hardware.
Post by Johann-Tobias Schäg
If not what would be necessary to port it to J2 (being SH2 + new atomic
CAS Instruction + back ported shift instructions from SH3)
Does newlib depend on features which require an mmu?
Please correct me if I'm wrong, but there's a way to override syscalls,
specifically *sbrk()?
https://www.embecosm.com/appnotes/ean9/ean9-howto-newlib-1.0.html
Sincerely Johann-Tobias Schäg
--
Dave.Nadler1
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