Yes this is correct! I am missing that period at the end of the first sentence. Thunderbolt can support two DisplayPort connections, but maybe his motherboard only has one DisplayPort connection to the Thunderbolt controller (like in my Gigabyte Z170X-Gaming 7). This can support 2560 x 1440 + 2560 x 1440 + 1920 x 1200 all at 60 Hz using just one DisplayPort connection. > last Thunderbolt 2 device -> MST hub -> three displays. So the device chain must be like this: Thunderbolt 3 computer -> Thunderbolt 3 to Thunderbolt 2 adapter -> first Thunderbolt 2 device ->. The TB3->TB2 adapter passes a Thunderbolt encapsulated DisplayPort stream that a Thunderbolt controller in a Thunderbolt device later in the chain can convert to DisplayPort. The MST hub must be connected to a Thunderbolt controller's DisplayPort output. After a couple of TB2 devices, a MST hub is used and it works fine with 3 monitors 3 ways down the chain. I think ha1o2surfer's statement is missing some punctuation and needs some slight rewording, like this: Like please map out the device chain, adapters, MST hub and monitors. From what it sounds like, what you are claiming to have done is impossible (TB3->TB2 adapters do not support DP alt-mode only DP through Thunderbolt protocol). seems that these emails are confidential. Linux kernel developers have contacts to a software engineering manager at Intel (Thunderbolt developer platform software team).ĮDIT: Oops. The best starting point is to look at Linux kernel patches: Thunderbolt/PCI code is not part of the open source version of the XNU kernel. I remember reading that macOS algorithm was more intelligent and that's why we can easily use multiple eGPUs. So it's all about fitting eGPU BARs within the bridge resource windows. The extra resources for the Thunderbolt bridges allows the kernel to find room for the new devices." In these other cases, only the exact amount necessary is allocated. This is in contrast to what most firmwares do, and what the Thunderbolt systems did for all non-Thunderbolt bridges. "One thing that both the PC and the Macs had in common was that they reserved space for additional devices on the hotplug slot as well as all upstream bridges as described in 2.2.2. Unfortunately Intel's Thunderbolt documents are under NDA, and I have no access to these. I didn't know anything about GPUs or (U)EFI programming a couple of years ago. I've been a regular software engineer for over a decade and have a MSc degree, my field of specialisation was information processing tech so wasn't a big leap to learn from Intel PDFs. If you know about this stuff then I would love to talk about it more if that is okay with you. This means there is still garbage that is motherboard-specific before it loads.Īlso, I am not sure if kexec syscall preserves bus initialisation - I would hope it is possible to load the target kernel into RAM, completely reset all of the bus states, and hand over to the other OS with a perfectly clean slate - so that the target OS is free to allocate things in the best way for its needs - rather than it being dictated. The LinuxBoot project looks promising, but it only loads at the DXE phase. Although far fetched, if it is possible to make a universal firmware that works on almost all motherboards, then I would be interestedĬlearly this is a vast amount to learn, but I am willing to pursue a career with low level architecture and design. Try and coerce target OS into allocating with IOMMU to avoid problems finding contiguous memory regions, and also for security. Thunderbolt handling from SMM -> OS kernel, allow for the AIC to work on any slot, including CPU lanes Cripple ME to bare minimum, completely wipe out SMM, AMT and ACPI (emulate bare minimum ACPI needed for Windows, hand over control of as much as possible with OSC, etc) Move as much stuff out of firmware as possible Understand if there is anything for which there is a good reason why the OS kernel cannot manage it (why it has to be in firmware) I am planning on taking courses for X86 architecture, UEFI and PCIe to learn enough to break this stuff apart.Īre you at a level such that you would understand this? You sound like you know a lot about this stuff.
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