Regarding Jumbo frame implementation in bge

Randall Stewart rrs at
Tue Nov 7 16:59:53 UTC 2006

sivakumar.subramani at wrote:
> Hi,
> In bge driver, we have BGE_JUMBO_FRAMELEN defined to 9018. 
> if_bgereg.h:#define BGE_JUMBO_FRAMELEN  9018
> This macro is used to allocate the memory for jumbo buffer. If I have
> a MTU size of 2000, still bge will allocate the jumbo buffer of size 
> BGE_JUMBO_FRAMELEN. Instead can we make the size to be depend on the 
> MTU. I mean instead of using BGE_JUMBO_FRAMELEN macro we can use MTU
> + IP header + CRC for Jumbo buffer size.
> Any reason for allocating a hard coded 9018 size all Jumbo MTU frame 
> (whether it is 9000 / 2000)?
> Thanks, ~Siva

Allocations are done via the zone managers.. and thus setup
at kernel boot. A value like the MTU is set dynamically...

So doing something like this would be questionable IMO.. I
am sure it could be done.. but I don't see the value.
In theory you have a waste for just a short time.. before
its m_free'd


Randall Stewart
NSSTG - Cisco Systems Inc.
803-345-0369 <or> 803-317-4952 (cell)

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