Filesystem support for qemu

[jhedberg]

I'd like to be able to do something like "make run FS=/some/host/path" and have the directory structure under /some/host/path become available inside qemu as persistent storage that can be accessed using the Zephyr file system APIs.

[andrewboie]

(01:14:40 PM) Anas: any idea if there is a way to emulate internal flash of an mcu with qemu? (#4911)
(01:18:02 PM) apboie: Anas: I know you can pass a disk image file to QEMU to use
(01:18:35 PM) apboie: -drive option
(01:18:59 PM) apboie: but that may or may not work, probably emulates a SATA device or something, not some memory-mapped flash
(01:21:01 PM) leandro.pereira: you can pass different interface types
(01:21:39 PM) leandro.pereira: -drive if=pflash,file=/path/to/some/flash/image.img
(01:22:08 PM) leandro.pereira: (not sure if pflash is what you're looking for, though.)
(01:25:18 PM) apboie: that seems the right ballpark

[carlescufi]

N/A

[mglettig]

@carlescufi @andrewboie What is the status on this topic? We try to achieve the same thing. So far we managed to mount a little FS filesystem on QEMU_X86. But we strugle on how to put data from the host system to the guest system (QEMU). I think the drive parameter would be the right approach but I can't see how to use it so that it gets detected by Zephyr.

[carlescufi]

@mglettig this is supported in native_posix instead, maybe that would be a solution for you?

[yashi]

@mglettig, it's quite easy to create a genlittlefs tool using its library. You can point to a generated file system image when you run qemu instance.

[mglettig]

@mglettig this is supported in native_posix instead, maybe that would be a solution for you?

Good idea. Unfortunately this is not possible in my case due to this bug here: #34226 So I'm currently stuck with QEMU.

@yashi This sounds very promising. How can I point to the generated file system image from QEMU? And how will my Zephyr application find this filesystem image so I can mount the Little FS filesystem? Any hints would be welcome.

[yashi]

@mglettig Oops, I meant native_posix instance, zephyr.exe. Not qemu. Sorry about that.