Subject: Re: M_READONLY
To: YAMAMOTO Takashi <>
From: Jonathan Stone <>
List: tech-net
Date: 09/20/2004 17:33:05
To me, the proposed change seems to be heading in the wrong direction.
We should aim to support more sharing of valid, non-mbuf kernel data
(e.g., data loaned from struct bufs) with subsystems which expect
mbufs chains; not less sharing.

From that perspective, the test for ``can I modify the kernel storage
backing this mbuf in-place?''needs to be stricter (less inclusive),
not more inclusive, since such `sharing' may involve non-mbuf
references to the same underlying storage.

In message <>,
YAMAMOTO Takashi writes:
>i'd like to change M_READONLY like the following.
>there's no point to protect external storage if it isn't shared.
>eg. receive buffers for jumbo frame.

[... patch, elided]