hey garrett,
some quick questions.
- this new functionality seems to be tied to the vnode/specfs layer
which is how userland and the ldi accesses devices, so presumably this
streams to cb_ops fall back behaviour will be supported for both userland
and ldi based device access? (i assume so.)
- will this fall back behaviour be supported for CLONE_DEV based minor
nodes? (i assume not.)
- once a device minor node is successfully opened, the underlying driver
must have decided on streams or cb_ops based access. so:
- if it decided on cb_ops accesses, will subsequent opens go
directly to the cb_ops open routine? (i assume so.)
- if it decided on streams access, is it valid for subsequent
open calls to return ENOSTR? (i assume not.)
- device open/close exclusion guarantees are implemented separately for
streams and cb_ops based access. presumably these guarantees will
still apply to devices that can switch between streams and cb_ops based
accesses? (in which case i guess the properties defined in
PSARC/2007/310 will be applicable to streams based drivers.)
- do you anticipate having individual minor device nodes that switch
between cb_ops and steams based access?
- instead of having the streams open entry point return ENOSTR to fall
back to cb_ops, did you consider adding a new flag to
ddi_create_minor_node() so that a driver could specify the desired
access semantics of a given minor node?
- what is the commitment level of this new ENOSTR interface?
ed
On Mon, Jul 06, 2009 at 08:55:44AM -0700, Garrett D'Amore - sun microsystems
wrote:
> I'm submitting the following case on my own behalf. Times out on 7/13/2009.
> This case seeks patch binding.
>
> Template Version: @(#)sac_nextcase 1.68 02/23/09 SMI
> This information is Copyright 2009 Sun Microsystems
> 1. Introduction
> 1.1. Project/Component Working Name:
> STREAMS and Character Device Coexistence
> 1.2. Name of Document Author/Supplier:
> Author: Garrett D'Amore
> 1.3 Date of This Document:
> 06 July, 2009
> 4. Technical Description
>
> STREAMS and Character Device Coexistence
> ----------------------------------------
>
