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Re: Unneeded SH4 boards

On Wed, 2015-10-28 at 11:05 +0100, John Paul Adrian Glaubitz wrote:
> On 10/28/2015 02:23 AM, Vladimir Zapolskiy wrote:
> > please correct me, if I'm wrong, but I believe Debian SH4 port is
> > practicably unusable for years.
> It's not, what makes you think so? I have invested lots of efforts
> recently to get the port back into shape and together with the
> help of upstream developers for the toolchain (gcc, binutils etc)
> and the kernel we managed to fix many bugs and got the boards
> running with recent kernel versions and gcc-5. I still continue
> working on the port.

The problem with the current SH4 debian, or actually with SH4*-linux
-anything is the model selection of atomic operations.  As far as I
know debian uses the default which is gUSA.  This is not so good for
SH4A systems... maybe we should fix this somehow in the near future.

Also, just out of curiosity ... which boards are supported by SH4
debian?  I'm not sure if a generic SH4 / SH4A Linux kernel is possible
at all..

> > The SH4 core architecture is pretty old, 

"Old is gold" :)

> > but I have some interest in its
> > support related to Open Hardware initiatives, but my problem is
> > that I
> > can not find any SH4 reference boards for sale (digikey has only
> > one
> > from Renesas, but its price is too high for me, about $800 for a
> > board
> > and LCD).
> Yeah, those boards are pretty hard to come by outside Japan. I visit
> Japan regularly but I always keep on forgetting looking for
> additional
> boards in Akihabara or other places.

A while ago I bought this

But I haven't had any time to make Linux work on it.  The images they
provided on Sourceforge use Linux Kernel 2.4 or 2.6 (don't remember)
and are probably not so useful anymore.  The vanilla Linux Kernel has
support for this board, but it enables only one core (out of 2 cores)
and L2 cache is also not enabled.  I don't know the reason, maybe some
of the SH4A multi-core stuff is not working properly.  As for the L2
cache, some other SH4A boards had problems and then people "fixed it"
by turning it off ...

Alpha Project has many other SH boards:

They also ship to outside of Japan.

Another interesting SH4A board is this:

The biggest drawback of those boards for running Linux is the
relatively small amount of RAM.  The prices are also not very hobbyist
friendly.  It's a very niche market (small demand = high price). 
 Probably you will not find anything for less than 500 USD.

I have a bunch of Dreamcast boxes and probably they are still easy to
get on eBay or other market places.  But with 16 MByte RAM it's
probably really difficult to get a usable Linux system running on it. 
 A PATA harddisk can be connected relatively easily, but transfer speed
is limited to something around 25 MByte/sec.  Ethernet is even more
difficult ...



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