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Function not implemented when using libaio
Hello
I experience "Function not implemented" errors when trying to use Linux libaio library in foreign architecture, e.g. aarch64.
I've faced this problem while using https://github.com/multiarch/qemu-user-static, i.e. Docker+QEMU.
I understand that I do not use plain QEMU and you may count this report as a "distribution of QEMU"! Just let me know what are the steps to test it with plain QEMU and I will test and update this ticket!
Here are the steps to reproduce the issue:
1) On x86_64 machine register QEMU:
`docker run -it --rm --privileged multiarch/qemu-user-static --reset --credential yes --persistent yes`
2) Start a Docker image with foreign CPU architecture, e.g. aarch64
`docker run -it arm64v8/centos:8 bash`
3) Inside the Docker container install GCC and libaio
`yum install gcc libaio libaio-devel`
4) Compile the following C program
```
#include <stdio.h>
#include <errno.h>
#include <libaio.h>
#include <stdlib.h>
struct io_control {
io_context_t ioContext;
};
int main() {
int queueSize = 10;
struct io_control * theControl = (struct io_control *) malloc(sizeof(struct io_control));
if (theControl == NULL) {
printf("theControl is NULL");
return 123;
}
int res = io_queue_init(queueSize, &theControl->ioContext);
io_queue_release(theControl->ioContext);
free(theControl);
printf("res is: %d", res);
}
```
```
cat > test.c
[PASTE THE CODE ABOVE HERE]
^D
```
`gcc test.c -o out -laio && ./out`
When executed directly on aarch64 machine (i.e. without emulation) or on x86_64 Docker image (e.g. centos:8) it prints `res is: 0`, i.e. it successfully initialized a LibAIO queue.
But when executed on Docker image with foreign/emulated CPU architecture it prints `res is: -38` (ENOSYS). `man io_queue_init` says that error ENOSYS is returned when "Not implemented."
Environment:
QEMU version: 5.0.0.2 (https://github.com/multiarch/qemu-user-static/blob/master/.travis.yml#L24-L28)
Container application: Docker
Output of `docker --version`:
```
Client:
Version: 19.03.8
API version: 1.40
Go version: go1.13.8
Git commit: afacb8b7f0
Built: Wed Mar 11 23:42:35 2020
OS/Arch: linux/amd64
Experimental: false
Server:
Engine:
Version: 19.03.8
API version: 1.40 (minimum version 1.12)
Go version: go1.13.8
Git commit: afacb8b7f0
Built: Wed Mar 11 22:48:33 2020
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.3.3-0ubuntu2
GitCommit:
runc:
Version: spec: 1.0.1-dev
GitCommit:
docker-init:
Version: 0.18.0
GitCommit:
```
Same happens with Ubuntu (arm64v8/ubuntu:focal).
I've tried to `strace` it but :
```
/usr/bin/strace: ptrace(PTRACE_TRACEME, ...): Function not implemented
/usr/bin/strace: PTRACE_SETOPTIONS: Function not implemented
/usr/bin/strace: detach: waitpid(112): No child processes
/usr/bin/strace: Process 112 detached
```
Here are the steps to reproduce the problem with strace:
```
docker run --rm -it --security-opt seccomp:unconfined --security-opt apparmor:unconfined --privileged --cap-add ALL arm64v8/centos:8 bash
yum install -y strace`
strace echo Test
```
Note: I used --privileged, disabled seccomp and apparmor, and added all capabilities
Disabling security solves the "Permission denied" problem but then comes the "Not implemented" one.
Any idea what could be the problem and how to work it around ?
I've googled a lot but I wasn't able to find any problems related to libaio on QEMU.
Thank you!
Martin
|