Re: [PATCH RESEND v6 10/36] multi-process: build system for remote device process

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Wed, Apr 22, 2020 at 09:13:45PM -0700, elena.ufimtseva@oracle.com wrote:
> From: Jagannathan Raman <jag.raman@oracle.com>
> 
> Modify Makefile to support the building of the remote
> device process. Implements main() function of remote
> device process.
> 
> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> ---
>  MAINTAINERS             |  8 ++++++
>  Makefile                |  2 ++
>  Makefile.objs           | 27 ++++++++++++++++++
>  Makefile.target         | 61 ++++++++++++++++++++++++++++++++++++++++-
>  accel/Makefile.objs     |  2 ++
>  backends/Makefile.objs  |  2 ++
>  block/Makefile.objs     |  2 ++
>  hw/Makefile.objs        |  7 +++++
>  hw/block/Makefile.objs  |  2 ++
>  hw/core/Makefile.objs   | 18 ++++++++++++
>  hw/nvram/Makefile.objs  |  2 ++
>  hw/pci/Makefile.objs    |  4 +++
>  hw/scsi/Makefile.objs   |  2 ++
>  migration/Makefile.objs |  2 ++
>  qom/Makefile.objs       |  3 ++
>  remote/Makefile.objs    |  1 +
>  remote/remote-main.c    | 23 ++++++++++++++++
>  stubs/replay.c          |  4 +++
>  18 files changed, 171 insertions(+), 1 deletion(-)
>  create mode 100644 remote/Makefile.objs
>  create mode 100644 remote/remote-main.c

This approach is okay for now but will result in a lot of Makefile
duplication in the long run.

Each hw .o file should specify its dependencies so that qemu-system-*
and the remote executable can link in the needed files.  The Kconfig
system can also help with this by enabling/disabling features.

Then the Makefiles don't need to duplicate *-obj-y and remote-pci-*.

> diff --git a/Makefile.objs b/Makefile.objs
> index f29c60c59d..f6654633b4 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -21,6 +21,33 @@ block-obj-$(CONFIG_REPLICATION) += replication.o
>  
>  block-obj-m = block/
>  
> +#########################################################
> +# remote-pci-obj-y is common code used by remote devices
> +
> +remote-pci-obj-$(CONFIG_MPQEMU) += hw/
> +remote-pci-obj-$(CONFIG_MPQEMU) += qom/
> +remote-pci-obj-$(CONFIG_MPQEMU) += backends/
> +remote-pci-obj-$(CONFIG_MPQEMU) += block/
> +remote-pci-obj-$(CONFIG_MPQEMU) += migration/

In the future migration can be split into the QEMU and remote parts.
The remote executable doesn't need all the live migration code.

> +remote-pci-obj-$(CONFIG_MPQEMU) += remote/
> +remote-pci-obj-$(CONFIG_MPQEMU) += accel/

Devices do not execute guest code so they should not need accel/.  kvm
and tcg functions were stubbed out earlier in this patch series, so I'm
surprised to see thing being built into the remote executable.

> @@ -121,6 +131,20 @@ LIBS := $(libs_cpu) $(LIBS)
>  
>  obj-$(CONFIG_PLUGIN) += plugins/
>  
> +ifeq ($(TARGET_NAME)-$(CONFIG_MPQEMU)-$(CONFIG_USER_ONLY), x86_64-y-)
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += accel/stubs/kvm-stub.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += accel/stubs/tcg-stub.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += accel/stubs/hax-stub.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += accel/stubs/whpx-stub.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/vl-stub.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/net-stub.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/monitor.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/replay.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/xen-mapcache.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/audio.o
> +remote-pci-tgt-obj-$(CONFIG_MPQEMU) += stubs/monitor.o
> +endif

Stubs don't need to be explicitly included, they should be linked in via
libqemustub.a.

> diff --git a/remote/remote-main.c b/remote/remote-main.c
> new file mode 100644
> index 0000000000..7c0764ad01
> --- /dev/null
> +++ b/remote/remote-main.c
> @@ -0,0 +1,23 @@
> +/*
> + * Remote device initialization
> + *
> + * Copyright © 2018, 2020 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu-common.h"
> +
> +#include <stdio.h>

This is already included by "qemu/osdep.h"

> +
> +#include "qemu/module.h"
> +
> +int main(int argc, char *argv[])
> +{
> +    module_call_init(MODULE_INIT_QOM);
> +
> +    return 0;
> +}
> diff --git a/stubs/replay.c b/stubs/replay.c
> index 2e3feee6a9..9b53c0cb37 100644
> --- a/stubs/replay.c
> +++ b/stubs/replay.c
> @@ -102,3 +102,7 @@ int replay_get_instructions(void)
>  void replay_account_executed_instructions(void)
>  {
>  }
> +
> +void replay_add_blocker(Error *reason)
> +{
> +}

This can be moved to the stubs patch.

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