Re: [Qemu-devel] [RFC][PATCH 0/5] backdoor: lightweight guest-to-QEMU backdoor channel

[Anthony Liguori]

On 09/29/2011 08:47 AM, Lluís Vilanova wrote:
> Provides the ability for the guest to communicate with user-provided code inside
> QEMU itself, using a lightweight mechanism.
>
> See first commit for a full description.
>
> Signed-off-by: Lluís Vilanova<address@hidden>

We already have two "backdoors" in QEMU: ivshmem and virtio-serial.  Can you 
discuss why these are insufficient for your purposes?

Also, what's the advantage of having a backdoor mechanism both for softmmu and 
user?  I can't think of a practical use-case for it.

Regards,

Anthony Liguori

> ---
>
> Lluís Vilanova (5):
>        backdoor: Add documentation
>        backdoor: Add build infrastructure
>        backdoor: [*-user] Add QEMU-side proxy to "libbackdoor.a"
>        backdoor: [softmmu] Add QEMU-side proxy to "libbackdoor.a"
>        backdoor: Add guest-side library
>
>
>   Makefile                       |    3 -
>   Makefile.objs                  |   21 ++++
>   Makefile.target                |    4 +
>   backdoor/guest/Makefile        |   18 ++++
>   backdoor/guest/common.c        |  130 +++++++++++++++++++++++++++
>   backdoor/guest/qemu-backdoor.h |   50 ++++++++++
>   backdoor/qemu/qemu-backdoor.h  |   29 ++++++
>   backdoor/qemu/softmmu.c        |  124 ++++++++++++++++++++++++++
>   backdoor/qemu/user.c           |  194 ++++++++++++++++++++++++++++++++++++++++
>   backdoor/qemu/user.h           |   17 ++++
>   bsd-user/main.c                |   25 +++++
>   bsd-user/mmap.c                |    7 +
>   configure                      |   35 +++++++
>   darwin-user/main.c             |   25 +++++
>   darwin-user/mmap.c             |    7 +
>   docs/backdoor.txt              |  144 ++++++++++++++++++++++++++++++
>   hw/pci.h                       |    1
>   linux-user/main.c              |   30 ++++++
>   linux-user/mmap.c              |    7 +
>   19 files changed, 869 insertions(+), 2 deletions(-)
>   create mode 100644 backdoor/guest/Makefile
>   create mode 100644 backdoor/guest/common.c
>   create mode 100644 backdoor/guest/qemu-backdoor.h
>   create mode 100644 backdoor/qemu/qemu-backdoor.h
>   create mode 100644 backdoor/qemu/softmmu.c
>   create mode 100644 backdoor/qemu/user.c
>   create mode 100644 backdoor/qemu/user.h
>   create mode 100644 docs/backdoor.txt