Re: [PATCH v5 12/50] multi-process: remote process initialization

[Jag Raman]

On 3/4/2020 5:29 AM, Dr. David Alan Gilbert wrote:
> * Jagannathan Raman (address@hidden) wrote:
> > Adds the handler to process message from QEMU,
> > Initialize remote process main loop, handles SYNC_SYSMEM
> > message by updating its "system_memory" container using
> > shared file descriptors received from QEMU.
> >
> > Signed-off-by: John G Johnson <address@hidden>
> > Signed-off-by: Elena Ufimtseva <address@hidden>
> > Signed-off-by: Jagannathan Raman <address@hidden>
> > ---
> >   v4 -> v5:
> >    - We checked if we could use functions already defined in
> >      util/main-loop.c instead of using g_main_loop_run. However,
> >      we couldn't find a suitable function that's generic enough
> >      to do this. All of them have emulator code embedded in them
> >      which is not used by the remote process. We are therefore
> >      not making any change to this patch
> >
> >   remote/remote-main.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 85 insertions(+)
> >
> > diff --git a/remote/remote-main.c b/remote/remote-main.c
> > index ecf30e0..56315cd 100644
> > --- a/remote/remote-main.c
> > +++ b/remote/remote-main.c
> > @@ -12,6 +12,7 @@
> >   #include "qemu-common.h"
> >   
> >   #include <stdio.h>
> > +#include <unistd.h>
> >   
> >   #include "qemu/module.h"
> >   #include "remote/pcihost.h"
> > @@ -19,12 +20,96 @@
> >   #include "hw/boards.h"
> >   #include "hw/qdev-core.h"
> >   #include "qemu/main-loop.h"
> > +#include "remote/memory.h"
> > +#include "io/mpqemu-link.h"
> > +#include "qapi/error.h"
> > +#include "qemu/main-loop.h"
> > +#include "sysemu/cpus.h"
> > +#include "qemu-common.h"
> > +#include "hw/pci/pci.h"
> > +#include "qemu/thread.h"
> > +#include "qemu/main-loop.h"
> > +#include "qemu/config-file.h"
> > +#include "sysemu/sysemu.h"
> > +#include "block/block.h"
> > +#include "exec/ramlist.h"
> > +
> > +static MPQemuLinkState *mpqemu_link;
> > +PCIDevice *remote_pci_dev;
> > +
> > +static void process_msg(GIOCondition cond, MPQemuChannel *chan)
> > +{
> > +    MPQemuMsg *msg = NULL;
> > +    Error *err = NULL;
> > +
> > +    if ((cond & G_IO_HUP) || (cond & G_IO_ERR)) {
> > +        goto finalize_loop;
> > +    }
> > +
> > +    msg = g_malloc0(sizeof(MPQemuMsg));
> > +
> > +    if (mpqemu_msg_recv(msg, chan) < 0) {
> > +        error_setg(&err, "Failed to receive message");
>
> Please give error messages more context, e.g. the device or process name
> or something like that so that; it helps when we get a user
> reporting a crash and they report 'Unknown command' in their log, but
> then we have to figure out where to point them.

Ah OK, we'll add the exec name & PID of the QEMU process that spawned
this remote process in the error messages.

Thank you!
--
Jag

> > +        goto finalize_loop;
> > +    }
> > +
> > +    switch (msg->cmd) {
> > +    case INIT:
> > +        break;
> > +    case PCI_CONFIG_WRITE:
> > +        break;
> > +    case PCI_CONFIG_READ:
> > +        break;
> > +    default:
> > +        error_setg(&err, "Unknown command");
> > +        goto finalize_loop;
> > +    }
> > +
> > +    g_free(msg->data2);
> > +    g_free(msg);
> > +
> > +    return;
> > +
> > +finalize_loop:
> > +    if (err) {
> > +        error_report_err(err);
> > +    }
> > +    g_free(msg);
> > +    mpqemu_link_finalize(mpqemu_link);
> > +    mpqemu_link = NULL;
> > +}
> >   
> >   int main(int argc, char *argv[])
> >   {
> > +    Error *err = NULL;
> > +
> >       module_call_init(MODULE_INIT_QOM);
> >   
> > +    bdrv_init_with_whitelist();
> > +
> > +    if (qemu_init_main_loop(&err)) {
> > +        error_report_err(err);
> > +        return -EBUSY;
> > +    }
> > +
> > +    qemu_init_cpu_loop();
> > +
> > +    page_size_init();
> > +
> > +    qemu_mutex_init(&ram_list.mutex);
> > +
>
> So these are some subset of the things from qemu_init; I guess
> we'll have to be careful when we add stuff to vl.c to think what should
> also be added here.
>
> Dave
>
> >       current_machine = 
> > MACHINE(REMOTE_MACHINE(object_new(TYPE_REMOTE_MACHINE)));
> >   
> > +    mpqemu_link = mpqemu_link_create();
> > +    if (!mpqemu_link) {
> > +        printf("Could not create MPQemu link\n");
> > +        return -1;
> > +    }
> > +
> > +    mpqemu_init_channel(mpqemu_link, &mpqemu_link->com, STDIN_FILENO);
> > +    mpqemu_link_set_callback(mpqemu_link, process_msg);
> > +
> > +    mpqemu_start_coms(mpqemu_link);
> > +
> >       return 0;
> >   }
> > --
> > 1.8.3.1
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK