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Re: [libvirt] [PATCH 02/16] Remote driver implementation of new migration API

On 05/12/2011 10:04 AM, Daniel P. Berrange wrote:
> * src/remote/remote_protocol.x: Define wire protocol for migration
>   protocol v3
> * daemon/remote.c: Server side dispatch
> * src/remote/remote_driver.c: Client side serialization
> * src/remote/remote_protocol.c, src/remote/remote_protocol.h,
>   daemon/remote_dispatch_args.h, daemon/remote_dispatch_prototypes.h,
>   daemon/remote_dispatch_ret.h, daemon/remote_dispatch_table.h:
>   Re-generate files
> * src/remote_protocol-structs: Declare new ABIs
> ---
>  daemon/remote.c              |  315 +++++++++++++++++++++++++++++++++++
>  src/remote/remote_driver.c   |  370 +++++++++++++++++++++++++++++++++++++++++-
>  src/remote/remote_protocol.x |   79 +++++++++-
>  src/remote_protocol-structs  |   90 ++++++++++
>  4 files changed, 847 insertions(+), 7 deletions(-)

ACK; your rebase looks sane.

> +struct remote_domain_migrate_begin3_args {
> +    remote_nonnull_domain dom;
> +    unsigned hyper flags;
> +    remote_string dname;
> +    unsigned hyper resource;
> +};

Unrelated to your patch, but do we need to think about the issues of
dealing with 32-bit platforms?

That is, if as a client on a 64-bit platform, connected to a 32-bit
server, I call virDomainMigrate(...,0x100000000), it gets correctly
transferred to the 64-bit hyper value over the wire.  But then on the
server side, the conversion of the 64-bit hyper back to a 32-bit long
corrupts the value I passed, and ends up calling virDomainMigrate(...,0).

In other words, I think we need some patches to our RPC protocol such
that all longs are passed as hyper (necessary to avoid penalizing
64-to-64 communication), but range-checked for 32-bits (necessary for
64-to-32 communication), with an appropriate error issued if the RPC
call can't proceed because of truncation issues.

Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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