USBUHCI/L Legacy USB Support notification

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USBUHCI/L Legacy USB Support notification

Postby davepaxton » Tue Sep 10, 2013 11:06 pm

Hello All,
As a beginner with the USB DOS applicationss/drivers can I ask for comments on the following before asking more detailed questions.
I am using a system with the following BIOS characteristics:-

Advanced BIOS features - shows system is prepared to boot from USB HDD/CD/FD/ZIP (presumably requiring legacy support)
but none of these is selected as a potential boot devices so presumably this implies legacy support not activated for the above devices. (Does anyone disagree with this assumption?)

Advanced Chipset features - shows USB Keyboard Support and USB Mouse Support items but both are currently disabled.

These are the only references that I could see related to "Legacy support" on this system. So with these BIOS settings I assumed no legacy support was enabled on this system.

However when loading USBUHCI/L after a fresh boot SOMETIMES it tells me I have legacy keyboard/mouse support enabled, BUT sometimes it does not.

Is this notification inconsistency seen by others? and is it of any consequence? or can I just skip this if USB functionality is OK (I do appreciate that I can switch notification off!)
Kind Regards
Dave Paxton
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Re: USBUHCI/L Legacy USB Support notification

Postby Bret » Wed Sep 11, 2013 4:13 am

Exactly what "legacy support" entails is different for each BIOS, but usually includes one or more of the following: keyboard, mouse, and disk drives. Technically speaking, legacy support should probably just be limited to keyboards and mice (that is all that is discussed in the early USB specs). The idea behind legacy support is to allow the user to configure and control the computer (configure the BIOS and use non-USB-aware operating systems like DOS) even when there are no legacy devices attached (PS2 mice and keyboards).

I definitely wouldn't classify booting from a USB disk as legacy support, though some BIOS manufacturers may disagree. It's debatable whether the ability to access a non-boot USB disk is really legacy support or not, though it's useful in any case.

I've not had problems with any of my computers being inconsistent about whether it thinks legacy support is enabled or not. The inconsistency may be related to cold boot vs. warm boot, where in a warm boot the BIOS doesn't fully "reset" the USB hardware like it should, particularly if legacy support is turned off and the BIOS is essentially "ignoring" the USB hardware.

The main purpose of the warning message in USBUHCIL is to inform you that your mouse and/or keyboard (and/or possibly the boot disk or current disk drive) may stop working after USBUHCIL is installed, and your system could instantly become useless (you need at least a keyboard to do anything useful on a computer in DOS). Telling USBVUHCIL to ignore this possibility with the appropraite command-line or environment variable option should cause no harm.

If the BIOS legacy support is controlling your keyboard (and possibly your mouse) and you want USBUHCIL to "take control" of the USB host controller that the keyboard is attached to, you need to install USBUHCIL, USBKEYB, and possibly USBHUB and USBMOUSE all at the same time using a batch file.
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Re: USBUHCI/L Legacy USB Support notification

Postby davepaxton » Wed Sep 11, 2013 4:43 am

Bret
Thanks for reply. I think you may have something with the cold/warm boot proposal and will check this out.
The thing is I thought I had suppressed/disabled any legacy support demand in BIOS and so did not expect any warning.
In fairness all seems to be working well so far.
Cheers
Dave Paxton
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Re: USBUHCI/L Legacy USB Support notification

Postby Thohean » Mon Mar 07, 2016 4:26 pm

Just wanted to add to this thread for anyone else looking for a way to disable the Legacy USB Support notification when loading the program, you have to add the disablelegacy switch to the loading line. Seams obvious after I figured it out, but looking at the /?, it doesn't indicate it also disables the notification.

Example code for autoexec.bat in windows 98:

LH /L:2 C:\DOS\USBDOS\usbUHCI disablelegacy
LH /L:2 C:\DOS\USBDOS\usbMOUSE
LH /L:2 C:\DOS\USBDOS\usbkeyb

For context:

I have a Compaq Deskpro EN SFF p600. The BIOS options are severely lacking and there is no option to disable USB legacy support.

Thanks Bret for the awesome program!
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Re: USBUHCI/L Legacy USB Support notification

Postby olcpu » Thu Jun 08, 2017 4:03 am

I also want to post here some experience with usbkeyb.
Probably it`s a wrong thread for it but I just won`t to create a new one only because of it.

I was searching for some USB-keyboard fix after booting from USB drive over PLOP boot manager (integrated in BIOS).
There is a known problem with USB-Keyboards support, just PS2 Keyboards seems to work after booting from USB drive over PLOP BM.
The Idea was to use for example USB flash drive with Free DOS on it too boot from and of course only USB keybaord.

At first I have tested it with IDE-SD card Adapter and SD card with Free DOS and this autoexec.bat:

USBUHCI /disablelegacy
USBKEYB

disablelegacy - I need to avoid confirmation request, because the BIOS (HP XW8000 workstation) also has legacy USB support but not for USB flash drives.

After that I could use my USB keyboard with some restrictions (for example Shift-combinations dosen`t worked). It means USBUHCI + USBKEYB works on the system!

And the main point I`ve tryed too boot from this SD over PLOP and USB Adapter and unfortunately after autoexec.bat finishd working I was unable to type anything in the command line :(

Any ideas/suggestions? :)
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Re: USBUHCI/L Legacy USB Support notification

Postby Bret » Mon Jun 12, 2017 5:45 am

I'm not sure what you mean by PLOP being integrated in the BIOS. I haven't checked out PLOP in awhile, but last I knew it wasn't integrated in any BIOS. Also, PLOP only allowed read access to the USB boot disk, not write access, and not access to any other USB devices (like mouse or keyboard).

It sounds like your problem is that you're trying to boot from a USB disk with PLOP, and then trying to have USBUHCI manage the same boot disk. There can be only one program (driver) managing each USB host controller. It can either be the BIOS, some kind of boot manager (like PLOP), or the Operating System. The program that is managing the USB host is also (at least indirectly) managing all of the devices attached to that host (disks, keyboards, USB hubs, mice, etc.). In the case of PLOP, it ignores all of the devices except the boot disk.

In order for USBUHCI to start controlling the host, it must disable the program that was managing the USB host and all of the devices attached to it (usually the BIOS, but in your case probably PLOP). As soon as USBUHCI disables the other program so it can start managing things, the disk stops working. You can't install new USB host drivers if the USB host you are trying to change is the one controlling the disk your driver files are on.

So, you either needs two USB host controllers (such as one for the boot disk that PLOP can manage and another for the other devices like keyboard and mouse and whatever that USBUHCI can manage), or you need two disks. The second disk could be something like a RAM disk, where you create the RAM disk, copy the USB driver files you need to the RAM disk, and install everything from the RAM disk. Note that this tends to screw your drive letters up (your boot disk probably won't be C: or A: any more), so you need to be very careful about what you're doing. There are also some DOS utilities (like SUBST and ASSIGN and others) that allow you to manipulate drive letters to some degree if that is an issue (a lots of times it is, especially in older DOS programs).
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Re: USBUHCI/L Legacy USB Support notification

Postby RooseveltS » Thu Nov 02, 2017 8:51 pm

Man that clarifies a lot of stuff for me so thanks for the explanation. I'm still unsure what to do though. I'm leaning towards the second disk.
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Re: USBUHCI/L Legacy USB Support notification

Postby tattum » Fri Aug 31, 2018 9:13 pm

I'm learning this as well. Thanks for the posting!
Also, check this list of the best dji drones in 2018-2019!
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