[ydl-gen] String instructions emulation on PPC970MP

[Patrice Bouchand]

Hello,

  I do not think my problem is related to this. I have no problem to run the
run code on the final target, once it succeeds to compile.
But anyway, thanks for the information and for your time.

       Regards

                  Patrice

2009/12/8 Derick Centeno <dcenteno at ydl.net>

> Hi Patrice:
>
> I did a little digging and came across the following explanation from IBM
> which explains that the CPU you are coding for (amcc440) requires a specific
> Linux capable of the following:
>
> In versions 2.6.26 and earlier of the Linux kernel, the code did not
> properly clear reserved bits 11 - 15 in word two of a Translation Lookaside
> Buffer (TLB) entry. These bits need to be set to zero as documented in the
> respective user’s manuals to avoid a degradation in performance.
> A change was included in Linux kernel version 2.6.27 which will clear
> reserved bits 11 - 15 bits in the finish_tlb_load function. With these bits
> automatically cleared, inadvertent performance degradation will be avoided.
> Users of the PPC440x6 and all 464 processor cores should use Linux kernel
> version 2.6.27 or later.
>
> You can read the document for yourself here:
>
>
> https://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/6F95C69A2ED9AE73002575AF005B6E4E
>
> YDL 6.2 does use kernel 2.6.27 (see here:
> http://www.fixstars.com/en/products/ydl/installed.html) however make sure
> that the settings recommended by IBM are in effect for the amcc440.
> However, that would mean that you are directly coding for that cpu not the
> native 970MP which comprises the PowerStation which would explain the
> problems you are reporting.
>
> IBM does have a document explaining coding for the 970MP (which are the
> native cpus within the PowerStation) and the Linux parameters they
> recommend.  That document is here:
>
>
> https://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/A0C294269DB8D1EC87256FF9004FC54C
>
> These are just preliminary references, of course, but I thought the
> information could be a useful start for you.  As for acquiring more details,
> you may have to confer with someone at Fixstars.
>
> All the best...
>
>
> On Tue, Dec 8, 2009 at 8:08 AM, Patrice B <pbfwdlist at gmail.com> wrote:
>
>> Hello,
>>
>>  I'm using a Power Station as a build machine to generate code for
>> amcc440 cpu using gcc 4.4 with option -mcpu=440fp. Since this release
>> of gcc, I notice that code is generated with string instructions which
>> are not supported by Power Station cpu, and then, it makes build
>> failed if a newly built binary needs to be run for a next build step.
>> Is there a way to emulate those instructions on a Power Station (which
>> currently runs YDL 6.0)
>>
>>  Best regards
>>
>>        Patrice
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>
>
>
> --
> =========
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>
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>
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