Although I can't assist with your problem, I would suggest that, if no
solution becomes available quickly, you could investigate the Asahai
Linux project and its Fedora integration. This would allow you to dual
boot your Mac by installing Linux alongside MacOS.
On 4/6/24 04:20, Yannick PLASSIARD wrote:
Dear all,
For a few weeks now, I have to use a Mac to do my job. I have two braille
devices:
- a Focus 5 USB device
- A VarioUltra 40 USB-HID device
Before that, I used these two devices on Windows and Linux without any
particular issues, either on a real Linux system with Brltty 6.6, or in a Linux
VM hosted by Windows with the same Brltty 6.6.
On MacOS however I noticed something strange with my VarioUltra device: the
transfer speed of the device (sending braille input / receiving braille dots to
print) is very very slow. For example, if I type characters quickly, the device
will freeze for several seconds and then the characters will be processed by
BRLTTY, making it very inconfortable to use.
About my current setup:
- Running latest macOS Sonoma on an ARM64 (m2Pro) chip
- Running latest VMWare Fusion software version to use a Linux ARM64 Debian
virtual machine
- Connect my braille device(s) to the VM and not to the Mac, so that BRLTTY can
see and interact with them.
My observations:
- Using the Focus 40 5th generation connected to USB, everything works very
well, nothing to complain about. I’m able to read and more importantly write
very quickly (typing at around 4 to 6 chars per second), and everything is
responsive.
- Using the VarioULTRA 40 connected to USB-HID to the same VM, things are very
sluggish: typing at the same speed will result in the situation described
above, i.e. slowness / freeze of the device until either a key is pressed, or a
certain time.
What I tried:
1) With the Focus 40:
- Works well everywhere: in a VM hosted by Windows/Mac, Linux host, and MacOS
Host using the screen driver.
2) With the VarioULTRA device: Works well on a Linux VM hosted by Windows and
linux Host, become sluggish on a Linux VM hosted by MacOS.
3) I tried to change hypervisors, and every software behaves the same, either
with UTM or VMWare Fusion (UTM can use either QEMU backend for virtualisation,
or Apple’s builtin virtualisation support).
4) I A few years ago, I noticed the very same behaviour with another USB-HID
device (Brilliant BI 40X) connected to a real Linux host, but unfortunately was
unable to investigate furthermore as I had this device for a couple of hours.
What I understood from the sources:
1) seems there is no Darwin HID support for now, so unable to test it with a
compiled version for this OS with a screen driver, like I did with the Focus 40
5th Generation.
2) It seems that the async_io stack which is responsible for scheduling
input/ouput events (and other things as well) does some polling so that it does
not actually « sleeps » for a given time before reading data from the device. I
tried to understand how timeouts are computed, to see if the issue could come
from this computation, but I’m still in the early stage of understanding this
stack and I currently did not find anything regarding this.
Therefore, here are my questions:
1) Does anyone using an USB-HID device already experienced such behaviours in
the past, and if so, did you manage to solve it?
2) Which logs would be necessary to investigate this furthermore (log
categories / level)?
3) If you’re thinking about something I did not try yet, feel free to point it
out, I’ll be happy to try it.
Many thanks in advance for your answers,
Best,
Yannick
_______________________________________________
This message was sent via the BRLTTY mailing list.
To post a message, send an e-mail to: [email protected]
For general information, go to: http://brltty.app/mailman/listinfo/brltty
_______________________________________________
This message was sent via the BRLTTY mailing list.
To post a message, send an e-mail to: [email protected]
For general information, go to: http://brltty.app/mailman/listinfo/brltty
