+1 On 11/30/09 00:05, Garrett D'Amore - sun microsystems wrote: > 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: > sdcard conversion to bd, EOF blk2scsa > 1.2. Name of Document Author/Supplier: > Author: Garrett D'Amore > 1.3 Date of This Document: > 29 November, 2009 > 4. Technical Description > > Background: > > PSARC 2007/654 introduced blk2scsa, as a common framework for exposing block > oriented devices as SCSI logical devices. PSARC 2007/659 introduced a > common framework for Secure Digital devices, building upon the blk2scsa > framework. PSARC 2009/646 offers a new, simpler, and more performant, > alternative to blk2scsa which does not depend on SCSI or the SCSA framework > at all. > > We would like convert the SDcard framework for SD and MMC memory cards to > use the new "bd" framework, and EOF the blk2scsa framework at the same time. > > This case seeks Minor binding. It depends on PSARC 2009/646, which is > not yet approved. > > > Architectural Details: > > In our prototype, we have converted the framework to express a single > persistent "bd" target, for each SDcard slot. The slot is a "removable" > drive. > > This implementation has a few notable ramifications: > > a) We can simplify the SDcard framework quite a bit > > b) There is no longer a need for a separate "sdcard" pseudo-nexus > 2009/648 (12/06/09) open sdcard conversion to bd, EOF blk2scsa > > driver. The "bd" device can appear as a direct child of the > SD host driver (e.g. sdhost). The "sdcard" driver will be removed. > > c) The target device will appear using a cXdYsZ notation, without a > a target number. > > d) Some performance ramifications from using larger transfers > will go away. Specifically, we can use large transfers even using > the raw device, and not have to fall back to PIO. (Because the > bd framework can break the transfers up for us.) > > e) As we do not currently support SDIO, there is no longer any > need to support the use of cfgadm with SDcard. The cfgadm > plugin for SDcard can thus be removed. (Note that at this point, > we find it unlikely that there will ever be sufficient motivation > to implement support for SDIO. While important for certain > devices such as mobile hand-sets, SDIO has no place on platforms > with a fully capable USB host or Express card implementation. > We have designed things in our prototype so that if SDIO support > were ever necessary it could be added back in without major > architectural changes to the memory card support.) > > This change will remove the ability to initiate a software reset > of the SDcard controller from the command line, but we have found > very little reason that such a capability is desirable. > > f) The sdcard framework itself will be able to eliminate all, or > nearly all, of its direct uses of the nexus DDI. (In the event > that SDIO support were added later, we would have to reintroduce > a lot of NDI interface consumption, though.) > > As part of this effort, we'd like to remove the blk2scsa layer specified > in PSARC 2007/654. There will be no more consumers for it, and the newer > bd framework specified in PSARC 2009/646 is superior to it. (The blk2scsa > interfaces are all Consolidation Private.) > > > 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 > >
-- --------------------------------------------------------------------- Rick Matthews email: Rick.Matthews at sun.com Sun Microsystems, Inc. phone:+1(651) 554-1518 1270 Eagan Industrial Road phone(internal): 54418 Suite 160 fax: +1(651) 554-1540 Eagan, MN 55121-1231 USA main: +1(651) 554-1500 ---------------------------------------------------------------------
