linux-kernel - Re: [Fwd: Re: upcall sample patch]

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Message-ID: <457866BF.6070503@us.ibm.com>
Date:	Thu, 07 Dec 2006 13:08:47 -0600
From:	Steve French <smfltc@...ibm.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: [Fwd: Re: upcall sample patch]

Steve French wrote:
> For the CIFS Kerberos/SPNEGO case the Kerberos ticket can end up 
> almost 64K in size and need to be passed down by Samba userspace 
> helpers to kernel (for sending over the kernel socket to the server in 
> the data area of the smb that the kernel cifs code formats).
>
> Is the limit on the Linux kernel connector really 1K for passing down 
> to kernel?
>
> On Wed, 2006-12-06 at 17:55 -0600, Steve French wrote:
>   
>> simo wrote:
>>     
>>> Steve,
>>> I am experimenting using netlink.
>>>
>>> I could v. easily send messages from user space to the kernel module,
>>> adapting the provided examples. I am finding some difficulty in
>>> understanding how the other way around is supposed to work though.
>>>
>>> However while digging into headers, I found that currently the maximum
>>> message size is set to 1024 bytes. That's a bit annoying.
>>>
>>>
>>>       
>> Linux kernel connector is the preferred netlink wrapper and it has
>> sample programs that I found.
>> Not sure the maximum size
>>     
>
> Steve I looked into the sample programs in 2.6.19, cn_test.c and ucon.c
> are provided. Unfortunately it is not clear from them how to make
> upcalls. It is very easy to make downcalls, but I found it hard to find
> out what's the right way to catch messages sent from the kernel in the
> user space. Do you have nay other examples?
>
> For the limit, just look in linux/connector.h there you can find a
> define that sets the MAX LEN of the message to 1024.
>
> Simo.
>   
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