Re: Console output stops on dbgp=xhci

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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On Wed, Sep 14, 2022 at 02:18:34PM -0400, Tamas K Lengyel wrote:
> Hi Marek,
> I'm testing the latest Xen master git branch
> (942ac5fc15ecc2f7ef1d9331c76d89d2cef10e5c) with the now merged xue
> patches.  My current boot command line includes dbgp=xhci@pci00:14.0
> console=dbgp and this works in that the Xen boot log shows up on the
> other side of the debug cable:
> 
> ...
> 
> (XEN) Dom0 has maximum 8 VCPUs
> 
> (XEN) ELF: phdr 0 at 0xffffffff81000000 -> 0xffffffff82c5cdac
> 
> (XEN) ELF: phdr 1 at 0xffffffff82e00000 -> 0xffffffff831a1000
> 
> (XEN) ELF: phdr 2 at 0xffffffff831a1000 -> 0xffffffff831d5000
> 
> (XEN) ELF: phdr 3 at 0xffffffff831d5000 -> 0xffffffff84000000
> 
> However, debug output on the USB3 port stops at this point. I would
> expect to see the same as xl dmesg shows:
> 
> (XEN) Dom0 has maximum 8 VCPUs
> (XEN) ELF: phdr 0 at 0xffffffff81000000 -> 0xffffffff82c5cdac
> (XEN) ELF: phdr 1 at 0xffffffff82e00000 -> 0xffffffff831a1000
> (XEN) ELF: phdr 2 at 0xffffffff831a1000 -> 0xffffffff831d5000
> (XEN) ELF: phdr 3 at 0xffffffff831d5000 -> 0xffffffff84000000
> (XEN) Initial low memory virq threshold set at 0x4000 pages.
> (XEN) Scrubbing Free RAM in background
> (XEN) Std. Loglevel: All
> (XEN) Guest Loglevel: All
> (XEN) *** Serial input to DOM0 (type 'CTRL-a' three times to switch input)
> (XEN) Freed 2048kB init memory
> ...
> 
> Do you have any idea what might be going on and preventing the output
> from showing over USB3 afterwards? The /dev/ttyUSB0 device is still
> present on the receiving side, just nothing is being received over it.

There are few more patches in the series that are de facto required.
Especially those about IOMMU, otherwise it can only possibly work with
iommu=0 (which I'm not sure if even is enough).

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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