I've been trying to get into QEMU development in order to virtualize a not supported hardware.
I want to develop a new QEMU i2c device (qemu x86), that would get/send data to an application running on the guest. Thing is : I need these data onto the host, as a daemon will send/get the same kind of data to the guest.
My questions are : is it easy to get the data from this device ?
Are there any examples already in QEMU that can fit my needs ?
PS : my i2c device is only a "bridge" between the host and the guest. I need the application to use i2c (can't change that).
Typically, the qemu device will use the "chardev" abstraction to get data from a socket on the host. For example, something like -chardev socket,path=/tmp/foo.sock,server,nowait,id=foo -device myi2c,chardev=foo will connect your i2c device to a socket on the host.
There are many examples of devices that use chardevs in QEMU's hw/char directory. A simple example is digic-uart.c.
Related
I possess the USRP X310 with a Basic TX daughterboard installed. My plan is to use it via 10GbE together with LabView with a Win10 host machine.
I have connected the SDR with an Ethernet cable using Port 0 and the included SFP adapter to my host PC's (1GbE) ethernet interface for network testing purposes. The ethernet adapter is configured to use the static IP 192.168.10.1. Furthermore I have installed the UHD (uhd_3.15.0.0-release_Winx64_VS2017.exe). However when the device is connected and powered on, I can neither ping 198.168.10.2 nor detect it running the uhd_find_devices.exe. I have also started the NI-USRP Configuration Utility which I recently updated but it was not able to detect the SDR either. I do observe that none of the LEDs on the back is illuminated (especially not the Port 0 ethernet).
How can I get it working?
If you've worked with other usrps (I have a few), then you'll find the X310 to be somewhat different, to the lower models.
Anyway, there are different fpga loads / images, which corrospond to whether you are trying to connect via a 1G or 10G module.
"The PCIe interface is always available regardless of what FPGA image is loaded. Ettus ships two FPGA image variants, the HG or HGS image which has one 1 GigE interfaces and one 10 GigE interfaces, and the XG image which has two 10 GigE interfaces.
So you need to be sure you have the right image to connect to it via 1GE... or I expect it won't work, as it seems to be.
HTH's.
I'm looking to write a simple Windows driver to enable running TCP/IP over a proprietary RF module. The module already provides Ethernet-style data packets with source/destination MAC, so I just need to layer IP packets (generated by the regular Microsoft IPv4 subsystem), set the MTU appropriately so they will be the right size, and then call the module's serial API. I'll need to be able to handle transmit statuses and implement an ARP protocol as well. I want the driver to expose a new interface similar to a wifi or ethernet card in Network Connections and use the normal Windows IP stack.
The module is UART and might be connected via FTDI chip, RS-232 converter, or native UART on an IoT Core board, so it will just be talking to a generic serial port. I am fine with only running on Windows 10, but I'm still not sure what to use. Can I use the UWP VPN provider? Do I need to write an NDIS miniport driver, or an interface provider? Also, how will I handle the driver needing complete control over the serial port at all times? I can't write a serial driver as it might be connected via many different types of serial ports.
I am modifying a monitor controller for a prototype. It would be convenient to send commands to the prototype using DDC/CI. In Windows, I can't find an obvious way to send a DDC/CI command to a "display dependent device".
The Monitor Configuration API can send virtual control panel commands, but it does not give access to display dependent devices (which would have an I2C address other than 0x6e).
Nicomsoft's WinI2C/DDC product seems to give access to a display dependent device, but it is end-of-life. I would prefer not to build a dependency on an end-of-life product.
NVIDIA's NVAPI has an I2C API, but I would like a solution that also works with Intel and AMD graphics adaptors.
A solution exists for windows which respect XDDM driver display model. Windows 8 and 10 use WDDM.
In XDDM there is a windows O.S. supplied video port driver, and the hardware vendor supplies a miniport driver. When the miniport driver call's the video port driver's edid helper api (VideoPortDDCMonitorHelper), the miniport must supply 4 i2c function pointers as arguments.
In order to utilize these interfaces however you must be acting as the video port driver. So you have to write a video port lower filter driver which just passes along all the interfaces on from the windows supplied video port driver to the miniport driver. Hook the api's and export them to a usermode driver or ioctl which an application can call.
It may be possible to simply mount an instance of the miniport driver and some how get it to call VideoPortDDCMonitorHelper. But with out the help of the actual video port driver it would be difficult to get guidance on how to do that. Also you would have 2 instances of the driver running which may be against the rules for windows.
It does not appear this solution works for windows 8 and 10 because they use a different display driver model which doesn't appear to expose low level control of i2c. It is internal to the miniport driver.
I have several assumptions in mind please correct me if I'm wrong:
Without a real IOMMU a DMA-Transfer would be a security risk, because a guest could transfer garbage in Host Memory.
A valid DMA-Transfer between guest memory and passthrough device without a real IOMMU is not possible.
The Host-OS is not aware of any DMA-related things related to the passthrough device
An now some questions:
related to Point 3: Is there a way to get any information about a DMA-Transfer with a passthrough device?
If I don't have DMA-Remapping on, would KVM complain about it?
Is there a possibillity to deny any DMA-related stuff for the guest with the passthrough device?
Ran across this old question while doing some research and figured I'd post an answer for anyone interested.
About point 1. Without an IOMMU you can't do passthrough at all. I/O devices are in the kernel space. The guest kernel is a user process that only thinks it is running in kernel space.
As to the questions:
With an emulated device the emulator code intercepts all of the DMA setup and can make sure they are valid. With PCI passthrough, the register reads and writes are going directly to the device, or to a VF on the device for SR-IOV, so there is no opportunity for KVM or any other code outside the guest to validate, give errors or complain.
I need to create a Cocoa app that will create a virtual serial port available to other apps, meaning registered in the IO Kit Registry.
Gist of the app:
Create a virtual serial port (listed in /dev and registered with the IOKit Registry)
Initiate a tcp connection out to another computer
Proxy everything received on the virtual serial port out to the
network and vice versa.
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.
I've done the test with socat/netcat/minicom to verify that it all works to proxy pty/tty traffic over the network but the tty I use doesn't show up as usable by random applications because it's not registered in the IO Kit Registry.
While I can use a pty/tty master/slave for the communication, I need this slave tty to show up to Mac applications. What would be very handy is a way to register a tty in the IO Kit Registry.
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?
Thank you for any help you can provide,
Stateful
First of all, have you checked if you can borrow a solution from this app? It's not obvious from the website if they've managed to get their virtual serial ports fully integrated into the system.
If there is a way to do it from user space, I'm not aware of it. The user-space IOKit API generally doesn't let you create class instances, let alone new device driver classes. Maybe you can somehow otherwise persuade the Cocoa libraries to find it despite not being registered in the kernel.
I don't know if you could get away with creating a "dummy" serial port in the kernel and then move your tty into its place in /dev from your userspace daemon. Maybe that's an option.
In case you do have to do it all in the kernel:
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.
Still, I think this is achievable as a first kernel project for an experienced C programmer (with some C++).
I hope that helps!