Re: [RFC PATCH v3 07/30] migration: Add fixed-ram URI compatibility check

[Peter Xu]

On Mon, Nov 27, 2023 at 05:25:49PM -0300, Fabiano Rosas wrote:
> The fixed-ram migration format needs a channel that supports seeking
> to be able to write each page to an arbitrary offset in the migration
> stream.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
> - avoided overwriting errp in compatibility check
> ---
>  migration/migration.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 28a34c9068..897ed1db67 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -135,10 +135,26 @@ static bool 
> transport_supports_multi_channels(SocketAddress *saddr)
>             saddr->type == SOCKET_ADDRESS_TYPE_VSOCK;
>  }
>  
> +static bool migration_needs_seekable_channel(void)
> +{
> +    return migrate_fixed_ram();
> +}
> +
> +static bool transport_supports_seeking(MigrationAddress *addr)
> +{
> +    return addr->transport == MIGRATION_ADDRESS_TYPE_FILE;
> +}

What about TYPE_FD?  Is it going to be supported later?

> +
>  static bool
>  migration_channels_and_transport_compatible(MigrationAddress *addr,
>                                              Error **errp)
>  {
> +    if (migration_needs_seekable_channel() &&
> +        !transport_supports_seeking(addr)) {
> +        error_setg(errp, "Migration requires seekable transport (e.g. 
> file)");
> +        return false;
> +    }
> +
>      if (migration_needs_multiple_sockets() &&
>          (addr->transport == MIGRATION_ADDRESS_TYPE_SOCKET) &&
>          !transport_supports_multi_channels(&addr->u.socket)) {
> -- 
> 2.35.3
> 

-- 
Peter Xu