[Bug 1891829] Re: High bit(s) sometimes set high on rcvd serial bytes when char size < 8 bits

[Thomas Huth]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:

    https://gitlab.com/qemu-project/qemu/-/issues

and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" or "Confirmed" within the next 60 days (other-
wise it will get closed as "Expired"). We will then eventually migrate
the ticket automatically to the new system (but you won't be the reporter
of the bug in the new system and thus you won't get notified on changes
anymore).

Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1891829

Title:
  High bit(s) sometimes set high on rcvd serial bytes when char size < 8
  bits

Status in QEMU:
  Incomplete

Bug description:
  I *believe* (not confirmed) that the old standard PC serial ports,
  when configured with a character size of 7 bits or less, should set
  non-data bits to 0 when the CPU reads received chars from the read
  register.  qemu doesn't do this.

  Windows 1.01 will not make use of a serial mouse when bit 7 is 1.  The
  ID byte that the mouse sends on reset is ignored.  I added a temporary
  hack to set bit 7 to 0 on all incoming bytes, and this convinced
  windows 1.01 to use the mouse.

  note 1:  This was using a real serial mouse through a passed-through
  serial port.  The emulated msmouse doesn't work for other reasons.

  note 2:  The USB serial port I am passing through to the guest sets
  non-data bits to 1.  Not sure if this is the USB hardware or linux.

  note 3:  I also needed to add an -icount line to slow down the guest
  CPU, so that certain cpu-sensitive timing code in the guest didn't
  give up too quickly.

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