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Re: Embedded and ARM Debian Sprint

Dnia niedziela, 7 listopada 2010 o 15:04:21 Luke Kenneth Casson Leighton 

>  i haven't looked around, but has anyone suggested adding a
> base64-encoded extension to the .deb name, containing a bit-field of
> "capabilities"?  the problem with splatting the capabilities into the
> .deb itself is that you then end up with dozens of combinations of
> capabilities, all with the exact same .deb filename.  by encoding the
> capabilities in the actual filename, you can still pick a particular
> package by its version number etc. etc. _but_ you can identify whether
> it will work on a particular CPU by decoding its capabilities bits.
>  0x1 -> v5, 0x2 -> v6 .... 0x10 -> NEON

On ARM it is quite simple: armv4t, armv4t-maverick, armv5te, armv5te-iwmmxt, 
armv6, armv6-vfp, armv6-t2, armv6-t2-vfp, armv7a, armv7a-neon, armv7a-neon-
iwmmxt2, armv7a-iwmmxt2 and few which I missed. 

Note that Debian do not supports armv4 cpus like StrongARM (for those you need 
to go for OpenEmbedded) but there are no devices on market with such oldies.
> and for x86, because, duh, you _so_ aren't going to get x86
> instructions on ARM CPUs :)
>  0x1 -> i586 0x2 -> i686 0x4->MMX 0x8-> MMX2

X86 is mess. You have mmx, mmxext, 3dnow, 3dnow-ext, sse 1/2/3/4/4a/5, cmov 
and few other features which can exists in one i686 but not in other i686 
(same with i586 chips).
> >  * Cross compilation environment (cross toolchains and target packages)

> as far as cross toolchains are concerned: openembedded has it all,
> done already.  why the f*** would you want to "start from scratch"
> when openembedded has everything that's needed??

Because Debian is Debian and OpenEmbedded is OpenEmbedded? They have different 
way of work. 

If you want to squeeze anything possible from cpu in embedded product then I 
would go for OpenEmbedded for any ARM cpu better then armv4t and worse then 
armv7a. Especially for EP93xx ones as OE allows to build single packages with 
optimizations to make use of Maverick FPU which is broken by design but can be 
used if toolchain is provided.

If you want to have thousands of packages available then go for Debian/Ubuntu. 
OE has lot of recipes but many things are incomplete or older or not present 
at all (KDE for example). Of course there are things in OE which are missing 
in Debian but that's life.

I use Debian since 1999 - on m68k, i386, amd64, arm, armel architectures. 
Ubuntu on amd64, i386, armel. OpenEmbedded since 2004 on arm, avr32, x86.

JID:      hrw@jabber.org
Website:  http://marcin.juszkiewicz.com.pl/
LinkedIn: http://www.linkedin.com/in/marcinjuszkiewicz

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