Hacks to get a working serial environment#1
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adventureloop wants to merge 6 commits intomhorne:udbc2from
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Hacks to get a working serial environment#1adventureloop wants to merge 6 commits intomhorne:udbc2from
adventureloop wants to merge 6 commits intomhorne:udbc2from
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For serial/parallel drivers.
- Add the udbc(4) client driver. - Add the "udbc" console backend to the UEFI loader. - Add the "udbcons" console backend to the kernel. - Add the /dev/udbcons device node. See https://wiki.freebsd.org/HirokiSato/xhci for more details. xhci: Support multiple xhci(4) devices hw.usb.xhci.dbc.pci_rid specifies PCI RID for the console. If not specified, the first found instance will be used.
Disable USBDBC for this loader variant, for the time being. Authored by: bz
We now use llvm-objcopy by default (as of commit 1cae712), but it does not support efi-app-x86_64 and similar ouptut formats (for more detail see LLVM issue 108609[1]). Go back to installing ELF Tool Chain's version of objcopy as elfcopy (the standard upstream name) and use it for EFI builds. [1] llvm/llvm-project#108609). PR: 280771 Reviewed by: andrew Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D49362
With these hacks (some are probably not needed), I am able to use xhci debug as a serial connection from both loader and the kernel. The target is a morefine m6 Intel N200 based system with an Alderlake-N based xhci controller and the host is a 13th Gen Framework 13 (that part shouldn't matter). The target is a virtual machine on the m6 running in bhyve with pcie passthrough of the xhci controller. I am using a Datapro xhci debug cable (USB 3.0 Super-Speed A/A Debugging Cable). https://www.datapro.net/products/usb-3-0-super-speed-a-a-debugging-cable.html
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Multiple issues existed within the powerpc FP/VSX save/restore functionality, leading to register corruption and loss of register contents in specific scenarios involving high signal load and use of both floating point and VSX instructions. Issue #1 On little endian systems the PCB used the wrong location for the shadowed FP register within the larger VSX register. This appears to have been an attempt to correct issue freebsd#2 without understanding how the vector load/store instructions actually operate. Issue freebsd#2 On little endian systems, the VSX state save/restore routines swapped 32-bit words within the 64-bit aliased double word for the associated floating point register. This was due to the use of a word-oriented load/store vs. doubleword oriented load/store. Issue freebsd#3 The FPU was turned off in the PCB but not in hardware, leading to a potential race condition if the same thread was scheduled immediately after sigreturn. The triggering codebase for this is Go, which makes heavy use of signals and and generates an unusual mix of floating point and VSX assembler. As a result, when combined with th powerpc lazy FPU restore, a condition was repeatedly hit whereby the thread was interrupted in FP+VSX mode, then restored in FP only mode, thus reliably triggering the issues above. Also clean up the associated asm() style issue flagged by GitHub Actions. Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com> MFC after: 1 week Pull Request: freebsd#1756
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I have a working test environment between a morefine m6 (alderlake-n xhci controller) and my framework 13.
These hacks are what I had to do to get a stable serial connection between the machines. I am yet to try live kernel debugging or testing to see which I can remove.