Can't get multi-process qemu to work

[Shunsuke Mie]

Dear QEMU folks,

I'm trying to run the multi-process QEMU, referencing to the document, 
but it is not work well.
document: https://www.qemu.org/docs/master/system/multi-process.html

The current status is that I couldn't find a remote device on pci bus 
from qemu.

The steps taken are as follows:

1. build qemu v6.2.0-rc2

2. prepare a program that creates a socket pair and exec shell.

```
$ cat pipe.c
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <stdlib.h>

int main(){
        int sv[2];
        if (!socketpair(AF_UNIX, SOCK_STREAM, 0, sv)){
                printf("%d,%d\n",sv[0],sv[1]);
                system("$SHELL");
        }
}

$ gcc pipe.c

$ ./a.out

```

3. check the socket pair

```
$ ls -alt  /proc/self/fd
...
lrwx------ 1 test users 64 12月 11 19:56 3 -> 'socket:[148118067]'
lrwx------ 1 test users 64 12月 11 19:56 4 -> 'socket:[148118068]'
```

4. run a qemu as remote machine that has scsi device

```

$ ./qemu/build/x86_64-softmmu/qemu-system-x86_64 -machine x-remote 
-nographic -D c.log -serial mon:stdio \
    -device lsi53c895a,id=lsi0 -drive 
id=drive_image2,file=./busybox/rootfs.img \
    -device scsi-hd,id=drive2,drive=drive_image2,bus=lsi0.0,scsi-id=0 \
    -object x-remote-object,id=robj1,devid=lsi0,fd=4 &

```

5.  run a qemu with x-pci-proxy-dev

```

$ ./qemu/build/x86_64-softmmu/qemu-system-x86_64 -m 2G -kernel 
./linux/arch/x86_64/boot/bzImage\
    -append 'console=ttyS0 root=/dev/sda rw init=/init' -drive 
file=./busybox/rootfs.clt.img \
    -serial mon:telnet:localhost:5556,server,nowait -nographic -D 
remote.log \
    -device x-pci-proxy-dev,id=lsi0,fd=3

...

# lspci
00:01.0 Class 0601: 8086:7000
00:00.0 Class 0600: 8086:1237
00:01.3 Class 0680: 8086:7113
00:03.0 Class 0200: 8086:100e
00:01.1 Class 0101: 8086:7010
00:02.0 Class 0300: 1234:1111

```

There is not scsi device in the list.


Is there other any documentations for the multi-process qemu?


Best regards,

Shunsuke