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    SubjectRe: [PATCH] crypto: compress - Add pcomp interface
    On Thu, 19 Feb 2009, Herbert Xu wrote:
    > On Thu, Feb 12, 2009 at 04:19:40PM +0100, Geert Uytterhoeven wrote:
    > > On Tue, 10 Feb 2009, Herbert Xu wrote:
    > > > On Thu, Feb 05, 2009 at 05:24:51PM +0100, Geert Uytterhoeven wrote:
    > > > > > Well with the netlink parameters these can have variable lengths
    > > > > > depending on how many parameters the user supplies.
    > > > >
    > > > > How can this be exported to userspace?
    > > > > How does this variable length parameter passing work? Do you have an example?
    > > >
    > > > See how we use it for rtnetlink, e.g., in net/ipv4/ip_gre.c.
    > > >
    > > > > Nothing in crypto/ seems to already use nla_*?
    > > >
    > > > Well we don't have a user-space API yet :) But checkout the
    > > > discussions on this list.
    > >
    > > I'm sorry, but this is a totally separate change, so I'm not going to do it
    > > right now.
    >
    > Sorry but I disagree. We're working on the user-space API right
    > now and having to redo the compression parameters API later because
    > we didn't take take user-space into account is just not acceptable.

    OK, I'll give it a try...

    > In any case, the nla stuff is not as hard is it looks. It's
    > going to add tens of lines to the setup code and that's it.
    >
    > In order to get started, all you need to do is call nla_parse.
    > You don't even need a policy for the simple attributes.
    >
    > Please let me know if you need more help in getting nla_parse
    > going.

    IIUC, my setup() routines should decode the parameters using nla_parse()?
    And the caller of a setup() routine should encode the data. But how? All the
    nla_put*() routines seem to be targeted at skb's.

    The only place where nla_parse() is called with a void */length pair is
    net/sched/em_meta.c:em_meta_change(). But I can find no place where the actual
    TCA_EM_META_* fields are encoded.

    Can you please explain? Thanks!

    With kind regards,

    Geert Uytterhoeven
    Software Architect

    Sony Techsoft Centre Europe
    The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

    Phone: +32 (0)2 700 8453
    Fax: +32 (0)2 700 8622
    E-mail: Geert.Uytterhoeven@sonycom.com
    Internet: http://www.sony-europe.com/

    A division of Sony Europe (Belgium) N.V.
    VAT BE 0413.825.160 · RPR Brussels
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