Laptop Linux at MITA Work in Progress

by William CatteyMassachusetts Institute of Technology

wdc@mit.edu

A 3-Part Talk

Part 1: A quick introduction to Athena

Part 2: Laptops

Part 3: Daunting Challenges

Part 1: A quick introduction to Athena

● Vision● Services● The Athena Value Proposition● Tension between UNIX-land and PC/Mac-land● Whither PC/Mac solutions● Athena porting experience● The Value of Linux

Vision

Back in 1983, the vision was to scale the kind of high performance computing done on minicomputers so that it could eventually be deployed to hundreds of individually owned systems.

Athena developed technologies and procedures to convert UNIX from a "one wizard per computer" model to a "one wizard per platform" model, and to deploy over 1000 systems identical enough to be maintained inexpensively, but different enough to be responsive to customer needs.

Services

Kerberos authentication: Athena brought you kerberos authentication that enabled secure communication on an insecure network populated with insecure machines.

Zephyr client-server instant messaging: Athena Zephyr does not have the pretty user interface of other systems, but was the first client-server instant messaging system and remains the leader in server scalability and clear security and authenticity of messages.

Hesiod lightweight directory access protocol. We did LDAP before LDAP did.

Services cont'd

Enterprise-wide file service: We started with remote virtual disk, replaced it with NFS to get platform independence, and migrated to AFS to achieve greater security and scalability. We didn't invent enterprise file service, but we learned the real requirements and helped drive the market in the right direction.

Install/Update: Through 20 years of the school of hard knocks we evolved a software deployment system that could accommodate multiple hardware vendors, multiple operating systems, application software, and non-disruptive system updates.

The Athena Value Proposition

The Benefit: Hundreds of systems cloned from a master software archetype that automatically receive non-disruptive updates.

The Cost: Adherence to open standards, and awareness of issues of security and scale.

The Challenge: Making sure that customers do not feel constrained by the parts of the system that "need to be the same for all".

Tension between UNIX-land and PC/Mac-land

The choice between Microsoft Windows and Linux on the laptop is informed by the mix of UNIX, Microsoft Windows and Mac operating system use at MIT.

Whither PC/Mac Solutions

PC's and Macs were originally ignored because they were expected never to become powerful enough to matter. Instead they evolved to a broader base of software, more graceful user interfaces, and larger installed base than ever expected by the Athena founders.

UNIX was surpassed by PC's and Macs in customer mindshare, diversity of applications, and ease of use by novices.

PC's and Macs evolved to match but not surpass UNIX in networking.

PC's and Macs have not yet caught up to UNIX, particularly Athena in the realm of large scale, low cost, maintainable deployment. We believe this is because the scalability value proposition of Athena has been ignored by an industry focused on other goals, and by a clientele unaware of what is possible. PC's and Macs come from a history of individual ownership - UNIX from a history of central administration.

Athena Porting Experience

Athena has most easily been ported to platforms adhering to open standards such as 4.3 BSD Unix, Linux, and Solaris. Platforms minimizing vendor-specific value added proved easiest.

Difficulties arise when interfacing to proprietary versions of services provided by Athena.

– Microsoft Windows has been the most challenging.

– SGI IRIX was next most challenging with its proprietary install system, inst, and its volatile code base.

– IBM AIX was next after SGI with the proprietary smit, hpfs, and HFT interface.

There is no longer an IRIX or AIX Athena.

There is a Windows Athena, but it takes more work than UNIX Athena to keep running, and to integrate new OS revisions.

The Value of Linux

Athena likes Linux. It's open, generic, and easiest to interface to. Compared to other platforms, its code base is actually reasonably conservative and stable where it matters to Athena services.

Part 2: Laptops

● The Laptop Value Proposition● Athena Work● Disconnected Operation for Athena● Services Affected● Architecture and Approach● Solutions● Open Issues

The Laptop Value Proposition

The Benefit: Mobility. Wireless nomadic computing was recognized as valuable from the day Alan Kay expressed the vision of the Dynabook.

The Cost: More individual responsibility for maintenance and administration. When this cost goes unpaid, users experience catastrophic system compromises, failures, and data losses.

The Challenge: To find appropriate implementations of Athena lessons learned to reduce maintenance and administrative burden with corresponding improvements in reliability.

Athena Work

The Athena Release Team helped qualify configurations recommended to customers for purchase.

Modifications to the generic Athena Linux install were made to accommodate Laptops.

User documentation for what to buy, and how to get Athena working on it was published.

The issues of sometimes disconnected operation were reviewed and began to be addressed.

Disconnected Operation for Athena

Up to now, Athena assumed the net was always there.

Could a way be crafted to continue to offer Athena services, particularly system update in the context of a sometimes disconnected machine?

PC and Mac disconnected operation is thus far better than Athena disconnected operation.

The Athena disconnected operation project

http://web.mit.edu/disco-athena/www/

surveyed the issues and began crafting solutions.

Services Affected

1. Name service

2. Email delivery

3. Network printing

4. Kerberized login

5. time synchronization

6. Auto update

7. Software delivery

8. Zephyr instant messaging

9. AFS File service

10. Backup

Architecture and Approach

We crafted an architecture for detecting network up/down events and forwarding those events to system demon for root-level tasks, and to a per-user demon for user-level tasks.

We do a little bit of fiddling with the implementations or configurations of certain services.

Solutions

1. Name service -- We hope to add a fast DNS timeout hack.

2. Email delivery -- We configure sendmail to queue, and flush the queue with the system demon.

3. Network printing -- Version 1 rejects network print jobs if no network present. Queueing and flushing are planned for version 2.

4. Kerberized login -- Use local accounts, and hook kerberos ticket renewal into the user demon.

5. time synchronization -- hooked into the system demon.

6. Auto update -- break into checkpoint-able chunks.

7. Software delivery -- local disk is your friend.

8. Zephyr instant messaging -- hook into the user and system demons.

9. AFS File service -- fast timeouts added.

10. Backup -- Remind users to connect up and do it by hand.

Open Issues

Detection of network up and down events still kludgey.

Linux lacks the graceful tools to:– switch network interfaces.– signal applications of shift to working offline.– offline operation of network filesystem.

Part 3: Daunting Challenges

● Difficulties with Laptop Linux● Issues in Linux support● Athena's Recommendations for Laptop Linux● A Constantly Shifting Landscape● Next Steps

Difficulties with Laptop Linux

The biggest difficulty is in handing users something that just works out of the box.

Just identifying systems for which a working release, and user documentation can be produced and kept up-to-date is a major challenge!

Issues in Linux support

Laptop systems often lack Linux support for:– current wired network chipsets.– current wireless network chipsets.– current graphics chipsets.– current sound chipsets.– power management.

Athena's Recommendations for Laptop Linux

In order to reap the benefits of the Athena value proposition on the laptop platform, the Linux support must be generic, not proprietary.

The current Athena Linux laptop offering involves extra hand-tooling to enable coexistence with a Microsoft Windows partition.

Continuing to offer an Athena Linux laptop product requires a sustained commitment to Linux support from the hardware vendor.

A Constantly Shifting Landscape

The IBM T30 of 2002 was a nearly ideal platform.

This year's product line seems to have gotten most things right, but losing the ability to do Linux wireless networking owing to no drivers for the Centrino wireless chip was disheartening.

We constantly worry in about the working relationship between graphics chip manufacturers and the XFreee86 developer community.

The PC market and particularly the laptop market looks likely to continue to have short life cycles for the underlying chipsets.

Microsoft coordinates closely with chip manufacturers, but the vendors of hardware that might run Linux have a variety of relationships.

Shifting cont'd

It is very difficult for a customer to have clear expectations in the face of changing hardware, and frequent regressions in functionality under Linux.

Can more be done to improve on this situation by either identifying a particular hardware configuration for longer lifespan, or by bringing more resources to bear to create closer coordination between the Linux software suppliers and the chip suppliers?

Next Steps

MIT continues to evaluate the cost/benefit ratio for:– UNIX vs Microsoft Windows– Laptop vs Desktop

The Athena Release Team has a lot of UNIX expertise. We do Linux today. Will the hardware support make that effort continue to be cost effective, or will we find an easier time with a different UNIX solution that embodies the IBM PowerPC microprocessor in a laptop...