Linux-kernel mailing list archive 1999-34,: dev_alloc_skb() magic headroom

# dev_alloc_skb() magic headroom

Henner Eisen (eis@baty.hanse.de)
Wed, 25 Aug 1999 01:02:02 +0200

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Hi,

dev_alloc_skb() allocates and reserves 16 extra bytes at the
skbuff's head. Is this just some magic code (for cache optimization,
protection against buggy drivers, ... what then???) subject to change
or can users (e.g. when allocating downstream skb's) rely on
dev_alloc_skb() always returning an skb with
16 extra bytes reserved at the buffer head?

I thought dev_alloc_skb() is primarily intended for network
device driver's interrupt handlers when allocation the upstream
skb's (the header won't grow when passed upstream). Is this true?

Henner

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