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SubjectRe: PATCH: Raw device IO for 2.1.131

On Tue, 15 Dec 1998, David S. Miller wrote:

> Just one situation I want clarified, do you think we'll be able to fit
> into our framework a way to (for example) get at the user's
> application level headers during a write (ie. http header, then the
> data)?

i can see 3 solutions:

2) if we are lucky: ie. the headers are predictable (ipv6, video)
or the hardware plays well too, we can splice the data flow before
the DMA is done, thus we can feed both user-visible buffers and
'content' buffers. (or in the case of vide, where frame size
is predictable, the mapping can be static) This is not always
possible.

1) we are smart: we put some _simple_ dataflow-changing
functionality into the kernel. The ability to parse very simple
and secure headers. Push anything more complex to user-space: it's
going to cost time anyway, it's complex ...

(this functionality might be in the card as well...)

the problem is with the VM again: the VM has page-alignment and
granularity issues, making 'data-flow splice' harder.

-- mingo



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