[Qemu-discuss] Using memory mapped IO to read and write in guest memory data

[lkn2993]

 

Hi all.

 

I have been searching thoroughly for the latest requirement I need to fulfill using QEMU.

The scenario is like this:

·         I have another simulator which is a C program, this program has a shared memory which can be exposed to a file when need be, it can also write to an address or read from it when required

·         I have a machine which runs FreeRTOS via QEMU, not the best operating system out there, I know. But it can accept interrupts and jump to the specified memory regions upon receiving it, so if QEMU has an address that I can write to using the external simulator application, then I can interrupt the OS to read the address for changes afterwards.

IMHO I have figured out that I can actually create MMIO to map an IO into memory address, but I cant seem to figure out the how tos that have been written to expose this feature.

 

·         So how can I actually initialize a memory mapped IO in qemu options(upon runtime or build)?

·         How can I read and write into it, The aforementioned C program can write freely to anything I desire, where and what should I write, where and how should I read(from memory mapped IO)

 

Are there also other alternatives to solve this problem? Like, can I actually use a file as the QEMU guest system memory and write to it and read from it with free will? Or is there a way to attach a process to QEMU that can see and edit its guest memory?

 

Thanks in advance.