VirtualBox

Ticket #5135 (closed defect: duplicate)

Opened 13 years ago

Last modified 13 years ago

Problem with Serial ports when transfer exceeds 256 bytes

Reported by: raccoonone Owned by:
Component: other Version: VirtualBox 3.0.8
Keywords: serial Cc:
Guest type: Linux Host type: Windows

Description

When passing through a connection to a serial device VirtualBox doesn't send the data correctly. If the device sends more than 256bytes of data at a time VirtualBox seems to buffer it into 256byte piece, and only sends a piece when there is a communication from the OS to the device. I'm running VirtualBox on a Windows XP host, with an Ubuntu Guest.

Change History

comment:1 follow-up: ↓ 2 Changed 13 years ago by frank

How is the serial port connected to the host (VM settings)?

comment:2 in reply to: ↑ 1 Changed 13 years ago by raccoonone

Replying to frank:

How is the serial port connected to the host (VM settings)?

I have it configured as: Port Number: COM8 Port Mode: Host Device

Anything else you need to know?

comment:3 Changed 13 years ago by raccoonone

This is still a problem in 3.0.10

comment:4 Changed 13 years ago by frank

Well, there is indeed buffering in the host part of the serial device implementation. The send buffer is 128 bytes long but as far as I can see, as soon as one byte arrives it is forwarded to the host's serial interface. But it can happen that the guest is sending too fast: If the buffer overruns, bytes will be dropped. Do you experience data loss or just bursts?

comment:5 Changed 13 years ago by raccoonone

Bursts. It will send all of the data from the device to the guest, if I keep "pinging" the device by sending some data from the guest to the device.

comment:6 Changed 13 years ago by raccoonone

This is still a problem in 3.0.12, do you need an additional information to debug this?

comment:7 Changed 13 years ago by replykate

I have the same problem. (sorry for my bad english I am french ). I tried to send a array (trame) from a windows xp host to a ubuntu (in VM). Only 258 bytes were send. If I try to send more, all my array is corrupted.

I tried to slow down transfert but no changement.

OS Host: WINDOWS XP SP3. OS Guest: Ubuntu 9.10. guest addon installed.

speed: 9600 bauds.

comment:8 Changed 13 years ago by TKreuzer

See also ticket #1548

comment:9 Changed 13 years ago by frank

  • Status changed from new to closed
  • Resolution set to duplicate

Let's close this as a duplicate. VBox 3.2.4 should definitely improve the situation.

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