On Sun, 10 Aug 2014 20:10:56 +0100 Joe <j...@jretrading.com> wrote: > On Sun, 10 Aug 2014 14:14:53 -0400 > Celejar <cele...@gmail.com> wrote: > > > On Sun, 10 Aug 2014 18:22:41 +0400 > > Reco <recovery...@gmail.com> wrote: > > > > > Hi. > > > > > > On Sun, 10 Aug 2014 17:09:58 +0300 > > > Martin T <m4rtn...@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 ... > > > > One of the reasons for the complication is that all ARMs are not > created equal. The ARM is not a processor, but a set of macros in a > semiconductor design language. Various manufacturers are licensed to > use the ARM core, and may add a variety of other hardware, effectively > as subroutines. The chip may have a numeric co-processor or not. So > there's no standardisation of hardware architecture such as the > 'IBM-compatible PC' ('will it run Lotus 123?') had thirty years ago. The > kernel needs to know what the composite chip contains and how to drive > it, and how it talks to the rest of the system. > > For example, the Raspberry Pi, a well-known small ARM-based computer, > uses a Broadcom 'System-on-Chip' processor, about which not much > information is available. The kernel of Raspbian isn't actually part of > Raspbian, but comes from the Raspberry Pi Foundation, and is closed > source, and presumably is proprietary to Broadcom. I suspect that few > ARM licensees provide full specifications of their devices.
Thanks. I understand the basic situation WRT ARM devices; I just don't know the specifics about device trees, flattened and non-flattened. Celejar -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20140810192752.113de5677c093321ad278...@gmail.com
