2017-12-01 4:25 GMT+01:00 Robert Nelson <[email protected]>: > On Thu, Nov 30, 2017 at 6:50 PM, <[email protected]> wrote: > > Hi, > > > > I'm just getting started on this great platform and I've got some > questions > > about capes/overlays on which I thought perhaps someone could share their > > expertise. > > > > Most of the documentation you find online still refers to cape manager > and > > slots, which is slightly confusing for beginners. I did find this page > [1] > > and I understand (I think) that there is no longer a cape manager and > that > > u-boot does the loading of capes. > > > > So first questions: > > > > - Is this assumption correct? > > Yes, > > > - I do understand the concept of the device tree and loading overlays, > > but... what is the difference between overlays, capes and virtual capes? > > I've seen all mentioned in various places, but nowhere could I find a > > description of each. I've also seen "manual overlays" mentioned. Do they > all > > actually refer to the same thing? > > Yes, > > > - How can one see which capes/overlays are loaded once the system has > booted > > up in the new uboot overlays world? > > Plug in a USB serial debug cable into the debug header, U-Boot is very > verbose about what loads.. >
Perfect, thanks a lot for all the answers. I guess the U-Boot output is not present in the kernel syslog as U-Boot loads the capes before the kernel starts. Quick questions on this, though: - Are there any plans to make reading the currently loaded overlays from userspace possible? E.g. similarly as they could be read before from the 'slots' file - Reading https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Where_did_the_slots_file_go.3F is this still the plan of action and is Stage 2 thus now complete? And regarding the loading of overlays: - What is the difference between the *uboot_overlay_addr{0..7}* and the *dtb_overlay* options in /boot/uEnv.txt? It seems they all can be used to specify a custom overlay to load on top of the universal cape overlay? > > > > > > I'm starting to look at the PRUSS and how to use them, and I'm not sure > > which overlays should be loaded to enable them, or if access to them is > > already enabled by default. On /boot/uEnv.txt there seem to be a couple > of > > options, one of which is commented out. I notice the difference in the > > naming ('*-RPROC-*', vs. *-UIO-* commented out), so I'm guessing that the > > RPROC PRUSS overlay is loaded and the UIO one is not. > > > > But could someone elaborate a bit more on this? > > > > ###PRUSS OPTIONS > > ###pru_rproc (4.4.x-ti kernel) > > uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-4-TI-00A0.dtbo > > ###pru_uio (4.4.x-ti & mainline/bone kernel) > > #uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo > > "uio" has been used since 3.8.x > > "pru_rproc" is TI's design, really only used with the "v4.4.x-ti" kernel. > > We try to eaisly allow you to swap betwen uio and pru_rproc > Thanks. - To be clear, when you say 'really only used with the "v4.4.x-ti" kernel' do you mean only with that particular kernel, or "v4.4.x-ti and later"? I'm just trying to understand which cape I should best use and which procedure (UIO vs. rproc) I should learn to start using the PRUSS. I also just learnt recently that there seems to be a "TI kernel" and a "Bone kernel". If I understand it correctly, the "TI kernel" is shipped by default on the Debian images and has TI patches, whereas the "Bone kernel" is effectively the mainline kernel. - Is this correct? - If so, what are their main differences? - Are they both maintained, and where is each repo? Regards. > > > Finally, on my /boot/uEnv.txt file I can see these lines, which I > understand > > are for older kernels. As a humble piece of feedback from a newcomer, > these > > make the file more confusing for options that no longer apply. Would it > not > > make sense to remove them for new images? > > > > ##Example v3.8.x > > #cape_disable=capemgr.disable_partno= > > #cape_enable=capemgr.enable_partno= > > > > ##Example v4.1.x > > #cape_disable=bone_capemgr.disable_partno= > > #cape_enable=bone_capemgr.enable_partno= > > Nope, as people still use 3.8.x and 4.1.x+ (pre u-boot overlays).. > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAGbJK0%3DsgqmXuBU7rAD5k5VHuZFzPbFSL%3D_47Ov4iE9io9b79g%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
