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Evangelism and Missions Team (EMT)

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Mac Os X Create Virtual Serial Port [UPDATED]

I'm trying to create a pair of virtual serial ports on my mac. This is fairly easy to do with many shareware programs on a PC. I figured there would be some uber-powerful shell command to do this in one line, but I can't find it.

Mac Os X Create Virtual Serial Port

When trying to import the current location using a GPS (or NMEA stream piped through our virtual serial port), we go: Tools > GPS > Realtime to get to the import screen.After selecting the NMEA option, and enabling realtime tracking, it looks for connected devices, and seems to look at:

I think what you are looking for is a Pseudo Terminal, as noted in Text-Terminal-HOWTO. It looks like Mac OS X has built in in /dev and it seems like this can do what you want to do, e.g. two programs talking together via a "virtual" serial port.

Pseudo terminals are pairs of devices such as /dev/ptyp3 and /dev/ttyp3. There is no physical device directly associated with either of them, not even a serial port connector. But if a program treats ttyp3 like it was a serial port, what is read and written to that port appears on the other member of the pair ptyp3 which another program uses to read and write to. Thus two programs talk to each other via this method and one program on ttyp3 thinks it's talking to a serial port. It's something like a "pipe" between these two tty's.

This app will be used by third party apps that talk to serial ports on the computer, allowing for the particular serial device to be located across the network. The Cocoa and network part is no problem, I've written several apps that talk over the network. My hangup is the serial port.

Do I really need to create a custom IOKit kext driver that gets registered at Cocoa app runtime? If so, I have a big learning curve ahead of me. Where should I start reading? Or, can I use IOKit to create a virtual serial port and register it as a usable serial port for applications without having to load any kernel extensions?

The virtual driver itself shouldn't be too much work, at least, though it will require some time to get up to speed with kernel dev. Unfortunately, the documentation is pretty thin for serial port drivers - the key is subclassing the IOSerialDriverSync abstract class. Just about the only description I've seen is in Ole Henry Halvorsen's OSX and iOS Kernel Programming book. It also has a fragment of an example for the reading & writing operations. (disclosure: I was one of the tech reviewers for this book; I don't receive any incentives for recommending it - in this case it's literally the only documentation I know of) You can find the source for a complete serial port driver in Apple's USBCDC driver, AppleUSBCDCDMM is the class that actually represents the serial port node.

It's relatively straightforward to open a so-called "kernel control" socket in the kernel, the individual APIs are documented here; from user space you use the normal BSD socket send/recv APIs. (this is also described in the aforementioned book) Your daemon can then connect to that, and all you'd need to do is push the data between the socket and the virtual serial port device. You'll need to handle disconnect events and such correctly of course.

I want to create virtual serial port which can be used to communicate between two application. I had tried with pty/tty pair(pseudoterminal) on mac. It worked also. But what i need it i want to configure it in such a way that other application could find it while doing the serial port search. Here i am stuck.

Chipset: You can select which chipset will be presented to the virtual machine. PIIX3 is the default chipset for most guests. For some guest OSes such as Mac OS X, the PIIX3 chipset is not well supported. As a result, Oracle VM VirtualBox supports an emulation of the ICH9 chipset, which supports PCI express, three PCI buses, PCI-to-PCI bridges and Message Signaled Interrupts (MSI). This enables modern OSes to address more PCI devices and no longer requires IRQ sharing. Using the ICH9 chipset it is also possible to configure up to 36 network cards, compared to a maximum of eight network adapters with PIIX3. Note that ICH9 support is experimental and not recommended for guest OSes which do not require it.

Pointing Device: The default virtual pointing device for some guest OSes is the traditional PS/2 mouse. If set to USB Tablet, Oracle VM VirtualBox reports to the virtual machine that a USB tablet device is present and communicates mouse events to the virtual machine through this device. Another setting is USB Multi-Touch Tablet, which is suitable for guests running Windows 8 or later.

However, software support for I/O APICs has been unreliable with some OSes other than Windows. Also, the use of an I/O APIC slightly increases the overhead of virtualization and therefore slows down the guest OS a little.

Hardware Clock in UTC Time: If selected, Oracle VM VirtualBox will report the system time in UTC format to the guest instead of the local (host) time. This affects how the virtual real-time clock (RTC) operates and may be useful for UNIX-like guest OSes, which typically expect the hardware clock to be set to UTC.

Processor(s): Sets the number of virtual CPU cores the guest OSes can see. Oracle VM VirtualBox supports symmetrical multiprocessing (SMP) and can present up to 32 virtual CPU cores to each virtual machine.

PAE stands for Physical Address Extension. Normally, if enabled and supported by the OS, then even a 32-bit x86 CPU can access more than 4 GB of RAM. This is made possible by adding another 4 bits to memory addresses, so that with 36 bits, up to 64 GB can be addressed. Some OSes, such as Ubuntu Server, require PAE support from the CPU and cannot be run in a virtual machine without it.

In most cases, the default settings on the Acceleration tab will work well. Oracle VM VirtualBox selects sensible defaults, depending on the OS that you selected when you created the virtual machine. In certain situations, however, you may want to change the preconfigured defaults.

Monitor Count: With this setting, Oracle VM VirtualBox can provide more than one virtual monitor to a virtual machine. If a guest OS supports multiple attached monitors, Oracle VM VirtualBox can pretend that multiple virtual monitors are present. Up to eight such virtual monitors are supported.

The output of the multiple monitors are displayed on the host in multiple VM windows which are running side by side. However, in full screen and seamless mode, they use the available physical monitors attached to the host. As a result, for full screen and seamless modes to work with multiple monitors, you will need at least as many physical monitors as you have virtual monitors configured, or Oracle VM VirtualBox will report an error.

You can modify these media attachments freely. For example, if you wish to copy some files from another virtual disk that you created, you can connect that disk as a second hard disk, as in the above screenshot. You could also add a second virtual CD/DVD drive, or change where these items are attached. The following options are available:

When you first create a virtual machine, Oracle VM VirtualBox by default enables one virtual network card and selects the Network Address Translation (NAT) mode for it. This way the guest can connect to the outside world using the host's networking and the outside world can connect to services on the guest which you choose to make visible outside of the virtual machine.

This default setup is good for the majority of Oracle VM VirtualBox users. However, Oracle VM VirtualBox is extremely flexible in how it can virtualize networking. It supports many virtual network cards per virtual machine. The first four virtual network cards can be configured in detail in VirtualBox Manager. Additional network cards can be configured using the VBoxManage command.

Ever since the original IBM PC, personal computers have been equipped with one or two serial ports, also called COM ports by DOS and Windows. Serial ports were commonly used with modems, and some computer mice used to be connected to serial ports before USB became commonplace.

While serial ports are no longer as common as they used to be, there are still some important uses left for them. For example, serial ports can be used to set up a primitive network over a null-modem cable, in case Ethernet is not available. Also, serial ports are indispensable for system programmers needing to do kernel debugging, since kernel debugging software usually interacts with developers over a serial port. With virtual serial ports, system programmers can do kernel debugging on a virtual machine instead of needing a real computer to connect to.

If a virtual serial port is enabled, the guest OS sees a standard 16550A compatible UART device. Other UART types can be configured using the VBoxManage modifyvm command. Both receiving and transmitting data is supported. How this virtual serial port is then connected to the host is configurable, and the details depend on your host OS.

Host Device: Connects the virtual serial port to a physical serial port on your host. On a Windows host, this will be a name like COM1. On Linux or Oracle Solaris hosts, it will be a device node like /dev/ttyS0. Oracle VM VirtualBox will then simply redirect all data received from and sent to the virtual serial port to the physical device.

Raw File: Send the virtual serial port output to a file. This option is very useful for capturing diagnostic output from a guest. Any file may be used for this purpose, as long as the user running Oracle VM VirtualBox has sufficient privileges to create and write to the file.

TCP: Useful for forwarding serial traffic over TCP/IP, acting as a server, or it can act as a TCP client connecting to other servers. This option enables a remote machine to directly connect to the guest's serial port using TCP. 350c69d7ab


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