Re: understanding Debian support on ARM architecture
On Sun, 10 Aug 2014 18:22:41 +0400
Reco <recoverym4n@gmail.com> wrote:
> Hi.
>
> On Sun, 10 Aug 2014 17:09:58 +0300
> Martin T <m4rtntns@gmail.com> wrote:
>
> > Reco,
> >
> > thanks for this explanation! Could you please explain this hardware
> > enumeration provided by x86/x86-64 CPU's to kernel bit more? What kind
> > of information is provided to kernel in case of x86/x86-64 CPU?
>
> Sure:
>
> 1) Obtain any x86 hardware.
>
> 2) Boot Linux.
>
> 3) Run lspci. Observe a non-empty result, which will probably include
> SATA, Ethernet, USB, Memory controllers and probably much more.
>
> 4) Repeat steps 1-3 with any ARM board (assuming successful boot, of
> course). Observe exactly one line that says (in my case, and that's
> good one, usually there's nothing at all):
>
> 00:00.0 Host bridge: Marvell Technology Group Ltd. 88F6281 [Kirkwood]
> ARM SoC (rev 03)
>
> And that particular hardware has at least Memory, Ethernet, 4-port
> SATA controller and USB.
>
>
> That's they mean then they talk about hardware enumeration - it's all
> there yet ARM platform has no means to discover it or to tell Linux
> kernel its there.
>
> So, you count the hardware, produce device tree, compile it into the
> kernel - and you can work with said hardware.
>
> You have a different set of hardware - you'll need a different device
> tree. And that means a different kernel.
Thanks for this explanation. I also run Debian on a Kirkwood platform
(a Seagate GoFlex Net (STAK100)) (in addition to my x86 hardware), and
I kept seeing all this talk about flattened device trees, and was aware
of the need for special kernels, but I never really understood why ...
http://forum.doozan.com/read.php?2,12096,12096
Now, I'm still not sure about the difference between flattened and
non-flattened trees, and what they're relative advantages and
disadvantages are ...
Celejar
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