mbuf question

[Hooman Fazaeli]

On 3/16/2014 3:08 AM, Hooman Fazaeli wrote:
> On 3/15/2014 9:09 PM, Rui Paulo wrote:
>> On 15 Mar 2014, at 00:48, Hooman Fazaeli <hoomanfazaeli at gmail.com> wrote:
>>> What about the area started at (m->m_ext + 1) whose size is (MHLEN - sizeof(struct m_ext))?
>>> Is there any known uses of this area in the stack?
>> I'm not sure what you mean by m_ext + 1, but what are you trying to do?  If you need to tag an mbuf, use mbuf tags.
>>
>> -- 
>> Rui Paulo
>
> (m->m_ext+ 1) points to the (unused?) area in m->m_dat.MHright after the space occupied by m_ext.
> I am well aware of mbuf tags. I was just thinking toavoid the overhead of m_tag allocation/de-allocation
> and store my little piece of data directly in mbufs.
>
sorry for my mistake. (m->m_ext + 1) is a totally wrong notation as m_ext is a struct.
The area I was talking about is (m->m_pktdat + sizeof(m->m_ext)).
Is this part of mbuf+cluster has any known uses? can we use it to store some
data about the packet (instead of using mbuf tags)?



-- 

Best regards.
Hooman Fazaeli