On Tuesday, 23 May 2023 16:03:28 CEST Philipp Eppelt wrote: > > The path you are on sounds correct. A reason for a missing DMA domain > resource on the vbus is (usually) the lack of a DMA capable device on > said vbus. > > https://github.com/kernkonzept/manifest/wiki/NVMeWithLinux#vbus-configuration-file > > shows a vbus configuration file that places all PCI/storage devices on > the vbus. I presume your MIPS board lacks PCI, so you have to write the > entries for System_bus and the Vbus yourself.
Yes, it involves a system-on-chip (SoC) without the usual PC architecture technologies like PCI. > The helpful sections in another tutorial are: > https://github.com/kernkonzept/manifest/wiki/HwPassThrough#ios-config-file > https://github.com/kernkonzept/manifest/wiki/HwPassThrough#vbus-configuration-file This is pretty similar to, but clearer than, the previous L4Re documentation about Io: https://l4re.org/doc/io.html > I found your mercurial instance for the l4re topic but didn't find any > io & vbus configuration. Can you point me to your config files? > And/Or send along the Io output with maximum verbosity (-vvvvvvv)? Thank you for going to the trouble of locating my repositories! Currently, there is no single location of the files for this effort, but I aim to tidy this up somewhat. To explain briefly, there is the set of patches to get the software working on these MIPS-based boards (which is thankfully diminishing over time), and then there is a framework called Landfall which contains example programs. You can see the .io file for the specific example program here: https://hg.boddie.org.uk/Landfall/file/7aa21a758551/conf/landfall-examples/ mips-ci20-hdmi-i2c.io Since it is short, here is the essential part: ---- local hw = Io.system_bus() local bus = Io.Vi.System_bus { CPM = wrap(hw:match("jz4780-cpm")); GPIO = wrap(hw:match("jz4780-gpio")); LCD = wrap(hw:match("jz4780-lcd")); HDMI = wrap(hw:match("jz4780-hdmi")); } Io.add_vbus("vbus", bus) ---- Meanwhile, the underlying board-level file is actually defined in a patch against L4Re, and it isn't currently in a public repository, but it just looks like this: ---- local Res = Io.Res local Hw = Io.Hw Io.hw_add_devices(function() CPM = Hw.Device(function() Property.hid = "jz4780-cpm"; -- compatible = {"mips,jz4780-cpm"}; Resource.regs = Res.mmio(0x10000000, 0x10000fff); -- Property.exclk_freq = 48000000; -- 48 MHz -- Property.rtclk_freq = 32768; -- 32.768 kHz end); DMA = Hw.Device(function() Property.hid = "jz4780-dma"; Resource.regs = Res.mmio(0x13420000, 0x1342103f); Resource.irq = Res.irq({59, 56}, Io.Resource.Irq_type_level_high); end); ... end) ---- Note that the DMA device in the above is actually the DMA controller peripheral which is used to perform DMA involving the different SoC peripherals. What I have tried to do in the .io file for the specific program is the following before the final statement adding the new bus as a vbus: ---- for resource in hw:resources() do print("resource name=" .. resource:id()); if resource:id() == 1145130308 then bus:add_resource(resource) end end ---- Here, I can confirm that there are two resources with the appropriate designation (1145130308, or 0x44414d44, or "DMAD"), and the trace from Io shows that the resource is copied to the vbus: IO | vbus: [N12_GLOBAL__N_112Virtual_sbusE] IO | Resources: ==== start ==== IO | DMADOM [00000000000000-00000000000000 1] (align=0 flags=6) IO | Resources: ===== end ===== IO | L4ICU: [N2Vi6Sw_icuE] IO | Resources: ==== start ==== IO | Resources: ===== end ===== IO | HDMI: [N2Vi9Proxy_devE] IO | Resources: ==== start ==== IO | IOMEM [00000010180000-0000001019ffff 20000] 32-bit non-pref (align=1ffff flags=300002) IO | IRQ [00000000000003-00000000000004 2] level high (align=1 flags=300001) IO | Resources: ===== end ===== But the DMA domain is still not found when assigning the space. I did wonder whether I might need to create a device to hold the DMA domain resource, but my attempt to implement this failed: for resource in hw:resources() do print("resource name=" .. resource:id()) if resource:id() == 1145130308 then device = Io.Vi.System_bus() device:add_resource(resource) bus:add_child(device) end end Here, Io crashes... IO | L4Re[rm]: unhandled read page fault at 0x31 pc=0x102aba0 IO | L4Re: rom/io: Unhandled exception: PC=0x102aba0 PFA=0x30 LdrFlgs=0x0 ...which is the following line in Dma_domain::add_to_group: if (!_v_domain && !g->_set) I imagine that I am making this harder than it should be, though. Paul _______________________________________________ l4-hackers mailing list l4-hackers@os.inf.tu-dresden.de https://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers
