I'm sponsoring this fasttrack for myself. Minor release binding is
requested. The timer is set for 02/06/2009.
-Artem
Template Version: @(#)sac_nextcase %I% %G% SMI
This information is Copyright 2009 Sun Microsystems
1. Introduction
1.1. Project/Component Working Name:
physical eject button
1.2. Name of Document Author/Supplier:
Author: Artem Kachitchkine
1.3 Date of This Document:
29 January, 2009
4. Technical Description
4.1. Summary
For years, operating systems have allowed users to unmount and
eject removable media by pressing the physical eject button located
on the drive's front panel. In fact, to a certain class of users,
that's the only way they know. We propose to add this feature to
Solaris such that pressing the button is functionally equivalent to
using eject(1) or mouse-clicking on the corresponding GUI primitive.
4.2. Details
device
|
| GET EVENT STATUS NOTIFICATION
v
scsi watch
|
| callback
v
sd driver
|
| sysevent
v
HAL (hald-addon-storage)
|
| DBus signal
/ \
/ \
GNOME rmvolmgr
4.2.1. Kernel
We propose to use the MMC-3 command GET EVENT STATUS NOTIFICATION
that reports, among other information: media presence, tray status,
and eject requests from the eject button. The same command is used
for media polling in Linux, FreeBSD and Windows (we verified
versions 98 and XP). So for target devices, Solaris host will
look very similar to the other hosts, which should minimize the
chances of incompatibilities due to undertested firmware, etc.
This command will be added to the kernel scsi watch facility, used
by sd(7D) driver to monitor media presence and implement dkio(7I)
DKIOCSTATE ioctl. Scsi watch periodically (every 3 seconds) sends
either a TEST UNIT READY or a zero-length WRITE to the device,
and based on returned status, sd determines if media is present.
We propose that scsi watch use GET EVENT STATUS NOTIFICATION on
target driver's request. Sd will prefer this command when: controller
type is CDROM, and device is MMC compliant, and positively responds
to GET EVENT STATUS NOTIFICATION command attempted during driver attach.
Otherwise sd will use the current mechanism. We will provide a new
SCSA function, scsi_mmc_watch_request_submit(), similar to the existing
scsi_watch_request_submit().
By using GET EVENT STATUS NOTIFICATION, sd can provide the very same
DKIOCSTATE functionality transparently to applications. In addition,
it can detect physical eject button presses and notify applications.
We propose that sd emit a sysevent when it detects an eject request:
Class: EC_dev_status - existing, introduced in PSARC/2006/373
Subclass: ESC_dev_eject_request - new, part of this case
Attribute: phys_path - device path
Even with careful implementation and testing, a small chance remains
of some MMC devices misbehaving when switched to the new polling
command. To facilitate diagnostics in the field, we propose a new
sd.conf boolean property 'mmc-gesn-polling': when set to false,
sd would use the old polling method for MMC devices.
4.2.2. Userland
The sysevent will be consumed by the hal(5) daemon, specifically its
storage add-on, responsible for monitoring media state and informing
applications via DBus. The HAL API already defines the "EjectPressed"
device condition, and GNOME volume manager/GVFS layer already support
it by initiating Eject() method in response to the condition.
This proposal requires no changes to the GNOME code.
Solaris also provides rmvolmgr(1M), the "console volume manager",
responsible for automounting in absence of the local desktop session.
We propose that rmvolmgr support the new feature, but it be disabled by
default, i.e. ignore the "EjectPressed" condition. Our reasoning is to
reduce the element of surprise in cases involving headless machines,
like accidentally pressing eject on a rack-mounted server, and
generally Solaris admins are used to the locked CDROM door with media
present. We will provide a boolean SMF property 'eject_button' for
svc:/system/filesystem/rmvolmgr:default: when set to true, rmvolmgr
will respond to the "EjectPressed" condition.
4.3. Interfaces
Exported:
--------------------------------+---------------+-----------------------
scsi_mmc_watch_request_submit | Cons. Private | scsi watch function
ESC_dev_eject_request | Committed | sysevent subclass
eject_button | Uncommitted | SMF property
mmc-gesn-polling | Uncommitted | sd.conf property
--------------------------------+---------------+-----------------------
Imported:
--------------------------------+---------------+-----------------------
EC_dev_status | Committed | sysevent class
EjectPressed | Volatile | HAL device condition
svc:/system/filesystem/rmvolmgr | Uncommitted | SMF service
--------------------------------+---------------+-----------------------
4.4. References
PSARC/2005/399 Tamarack: Removable Media Enhancements in Solaris
PSARC/2006/373 Dynamic LUN Expansion
SCSI Multimedia Commands - 3 (MMC-3)
http://www.microsoft.com/whdc/device/storage/GESN_Imp.mspx
6. Resources and Schedule
6.4. Steering Committee requested information
6.4.1. Consolidation C-team Name:
ON
6.5. ARC review type: FastTrack
6.6. ARC Exposure: open
