USB 15 port limit or 26 port limit?

[c-o-pr]

I've been perusing Dortania status and saw this in the z590 Status

Z590 RKL support #221

Z590 RKL support · Issue #221 · dortania/bugtracker

We need to update https://dortania.github.io/OpenCore-Install-Guide/ to include Z590 information. Here is a reference config, which can be of some help. There also are notes: https://dortania.githu...

github.com

Which leads to Dortania Rocket Lake / z590 Status...

Intel Z590 compatibility with macOS

Intel Z590 compatibility with macOS

As I mentioned earlier in the monthly release notes blogpost, over the last weeks we did a great job with @vandroiy2013 in testing Intel Z590 with Comet Lake (10th generation) and Rocket Lake (11th generation) CPUs. While our experience was generally positive it was still full of unexpected...

dortania.github.io

Which includes...

//USB support: The amount of USB ports does not fit the 26 port limit (2.0 + 3.x) just as usual. Without the plist-only kext describing every USB port in most cases even the basic macOS Installer will be uncontrollable through the mouse and keyboard regardless of the port limit quirks. To workaround it creating a plist-only kext with just the first 26 USB 2.0 and USB 3.x devices is highly recommended. Such an action should be enough to get the mouse, the keyboard, and the USB media work in at least some ports to perform the installation and configure all the devices properly.//

Can anyone here offer an explanation for why a key Acidanthera developer (vit9696) describes the USB port limit is 26 but everyone here thinks the USB limit is 15?

Or help with context, as this seems like a complete surprise to me, but maybe I'm missing something basic...

 

[etorix]

A "26-port limit" appears in Dortania's guide for USB mapping:

Why should you USB map | OpenCore Post-Install

Careful reading suggests it might relate to a hardware limit on the possible number of USB ports from the chipset, although 26 does not square with the number of USB 2.0 ("up to 14") and USB 3.x ("up to 10") ports listed in ark.intel.com for Z170 and its successors all the way to Z690. But with the 2 USR ports which macOS never uses anyway, that would be 14 HSxx (USB 2.0) + 2 USRx + 10 SSxx (USB 3.aargh!) = 26 possible ports in ACPI.
And then macOS adds its own software limit of 15 ports on top of that.

 

[UtterDisbelief]

I've been perusing Dortania status and saw this in the z590 Status

Z590 RKL support #221

Z590 RKL support · Issue #221 · dortania/bugtracker

We need to update https://dortania.github.io/OpenCore-Install-Guide/ to include Z590 information. Here is a reference config, which can be of some help. There also are notes: https://dortania.githu...

github.com

Which leads to Dortania Rocket Lake / z590 Status...

Intel Z590 compatibility with macOS

Intel Z590 compatibility with macOS

As I mentioned earlier in the monthly release notes blogpost, over the last weeks we did a great job with @vandroiy2013 in testing Intel Z590 with Comet Lake (10th generation) and Rocket Lake (11th generation) CPUs. While our experience was generally positive it was still full of unexpected...

dortania.github.io

Which includes...

//USB support: The amount of USB ports does not fit the 26 port limit (2.0 + 3.x) just as usual. Without the plist-only kext describing every USB port in most cases even the basic macOS Installer will be uncontrollable through the mouse and keyboard regardless of the port limit quirks. To workaround it creating a plist-only kext with just the first 26 USB 2.0 and USB 3.x devices is highly recommended. Such an action should be enough to get the mouse, the keyboard, and the USB media work in at least some ports to perform the installation and configure all the devices properly.//

Can anyone here offer an explanation for why a key Acidanthera developer (vit9696) describes the USB port limit is 26 but everyone here thinks the USB limit is 15?

Or help with context, as this seems like a complete surprise to me, but maybe I'm missing something basic...

@etorix is correct.

The chipset port limit is the 24x ports Intel gives us, but common ACPI tables, provided in BIOS by motherboard manufacturers, include 2x USR ports as well. Perhaps as "spacers", perhaps "just in case".

What I believe the OpenCore dev is saying is that keyboard and mouse will not function during boot without a pre-configured USB port map as the port(s) that might be providing a USB connection to them, or bluetooth radio for them, will probably be inactive thus rendering them inoperative.

To get around this, in the "old days" we would use USBInjectAll.kext and a port-limit removal patch. This would open up all 26x ports making sure the keyboard and mouse were operational.

An alternative to this was to use the XhciPortLimit quirk, but this has stopped working correctly since Big Sur 11.3. So the third method is to define a USBPorts.kext / USBMap.kext / USBToolBox.kext (your choice) with all 26x ports configured.

Once up and running you would then configure down to the 15x limit.

 

[c-o-pr]

If I follow you, my reading might be confusing the context of a 26 port upper limit regarding gaining access to key/mouse for install with a post-install 15 port limit for solid operation...?

 

[etorix]

As @UtterDisbelief and I understand it, the sole true "limit" is 15 ports, set by macOS. 26 ports is more a "pool" or a "potential" of possible ports—and Intel could presumably raise it at any time (say, 34 ports in Z790 to have more lanes for more USB 3.2 Gen 2x2).
The wording in Dortania's guide is unfortunate, and there could be more explanations for the figure 26.