* Common kernel image for e300 and e500v2
@ 2009-01-23 15:05 Johns Daniel
2009-01-23 16:21 ` Scott Wood
0 siblings, 1 reply; 4+ messages in thread
From: Johns Daniel @ 2009-01-23 15:05 UTC (permalink / raw)
To: linuxppc-dev
Is it possible -- and prudent -- to use a single kernel binary image
for two similar boards, one based on an e300 core and the other on an
e500v2 core?
I was surprised to see that the e500v2-targeted toolchain did build
the kernel for the e300 board just fine. Don't know whether this will
always be true?
The next logical step was to configure and customize the kernel just
right so that a single binary image will work on both boards. I am not
sure this is possible -- and, even if possible, whether this is
kosher!
Would love to hear the technical nuances involved with this...
-- Johns
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Common kernel image for e300 and e500v2
2009-01-23 15:05 Common kernel image for e300 and e500v2 Johns Daniel
@ 2009-01-23 16:21 ` Scott Wood
2009-01-23 17:31 ` Johns Daniel
0 siblings, 1 reply; 4+ messages in thread
From: Scott Wood @ 2009-01-23 16:21 UTC (permalink / raw)
To: Johns Daniel; +Cc: linuxppc-dev
Johns Daniel wrote:
> Is it possible -- and prudent -- to use a single kernel binary image
> for two similar boards, one based on an e300 core and the other on an
> e500v2 core?
No, it is not possible. They use different MMUs, and the kernel does
not support choosing between them at runtime.
> I was surprised to see that the e500v2-targeted toolchain did build
> the kernel for the e300 board just fine. Don't know whether this will
> always be true?
"always" is a strong word, but it should generally work.
-Scott
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Common kernel image for e300 and e500v2
2009-01-23 16:21 ` Scott Wood
@ 2009-01-23 17:31 ` Johns Daniel
2009-01-23 18:42 ` Scott Wood
0 siblings, 1 reply; 4+ messages in thread
From: Johns Daniel @ 2009-01-23 17:31 UTC (permalink / raw)
To: linuxppc-dev
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Thank you for that piece of info, Scott!
May I expand the question one bit, and ask whether the user-mode binaries
compiled for the e300 will generally work for the e500 -- or, vice versa? Is
one choice safer than the other?
I know for sure that we take a big hit on floating-point ops, but are there
other things I am not considering?
-- Johns
On Fri, Jan 23, 2009 at 10:21 AM, Scott Wood <scottwood@freescale.com>wrote:
> Johns Daniel wrote:
>
>> Is it possible -- and prudent -- to use a single kernel binary image
>> for two similar boards, one based on an e300 core and the other on an
>> e500v2 core?
>>
>
> No, it is not possible. They use different MMUs, and the kernel does not
> support choosing between them at runtime.
>
> I was surprised to see that the e500v2-targeted toolchain did build
>> the kernel for the e300 board just fine. Don't know whether this will
>> always be true?
>>
>
> "always" is a strong word, but it should generally work.
>
> -Scott
>
>
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Common kernel image for e300 and e500v2
2009-01-23 17:31 ` Johns Daniel
@ 2009-01-23 18:42 ` Scott Wood
0 siblings, 0 replies; 4+ messages in thread
From: Scott Wood @ 2009-01-23 18:42 UTC (permalink / raw)
To: Johns Daniel; +Cc: linuxppc-dev
Johns Daniel wrote:
> Thank you for that piece of info, Scott!
>
> May I expand the question one bit, and ask whether the user-mode
> binaries compiled for the e300 will generally work for the e500 -- or,
> vice versa? Is one choice safer than the other?
>
> I know for sure that we take a big hit on floating-point ops, but are
> there other things I am not considering?
It should work, though as you note floating point will have to be
emulated (make sure your kernel supports it); better would be to compile
as soft-float. Also avoid string instructions.
-Scott
^ permalink raw reply [flat|nested] 4+ messages in thread
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2009-01-23 15:05 Common kernel image for e300 and e500v2 Johns Daniel
2009-01-23 16:21 ` Scott Wood
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2009-01-23 18:42 ` Scott Wood
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