LWN.net Weekly Edition for May 9, 2013

The problem

After the Fedora 19 alpha release, the installer developers decided to stop masking the passwords supplied by the user during the installation process. Passwords only remained visible for as long as the keyboard focus remained on the relevant input box; as soon as the focus moved on, the password would be masked. But that still left the password visible for an arbitrary period of time to anybody who chose to look.

Some users, suffice to say, were unamused. A bug report was filed — and promptly closed:

The above-mentioned unamused users were, strangely enough, equally unamused by this response. The bug was reopened, and the massive mailing list discussion was launched. The arguments covered whether it ever made sense to show passwords in the clear, whether passwords still make sense at all, and more. The new behavior had few defenders, a trend not helped by the near absence of the Anaconda developers from the discussion. On May 6, the change was reverted with no explanation. At that point, naturally, the discussion was done.

Heard in the debate

While there was a lot of talk about the security issues associated with the clear display of passwords, there was also a lot of meta-discussion on how issues like this should be handled. Some participants, Matthew Garrett in particular, took issue with the tactic of reopening the bug entry:

Anybody who spends any significant time reading bug tracker entries knows that they often host spirited debates about the merits of specific changes. These entries can serve as a focal point for a discussion of a particular issue that the relevant developers will have a relatively hard time ignoring. On the other hand, bug trackers can be painful places to hold any kind of detailed discussion. They tend to have all of the disadvantages of forum sites, without the polished interfaces and enhanced searchability that such sites provide. A desire to keep such discussions on the mailing lists — and to avoid using the bug tracker to bug the relevant developers — is understandable.

A few people tried to bring up matters of policy, claiming, understandably, that policies are a big part of what distinguishes a distribution from a random collection of software. Fedora does not appear to have an explicit policy on how password forms should behave. Perhaps it should: it would be better if such forms behaved consistently throughout the distribution rather than surprising users with occasional novelties. Eric Sandeen suggested that Anaconda's unique role in the distribution should maybe subject it to more scrutiny than other packages, asking "How much of the Anaconda team's job is it to set Fedora OS policies and behaviors, vs. to implement them?" He pointed out that a decision by the Anaconda developers to change the default filesystem used with new installs would probably not be seen as an Anaconda-only matter, for example.

It was suggested that the issue could be forwarded to the Fedora Engineering Steering Committee (FESCo) in an attempt to force the change to be reverted. FESCo member Kevin Fenzi expressed the low level of enthusiasm most participants seemed to feel for that approach:

Fedora, arguably, does not defend the independence of its package maintainers as fiercely as, say, Debian does. But a developer's package still tends to be their castle; even those who were opposed to this particular change were, for the most part, unwilling to try to revert it by force. As a community, we remain disinclined toward dictating instructions to our developers.

The discussion clearly covered a number of ways in which this particular technical decision should be debated and decided. The one thing it did not do, unfortunately, is provide any indication of how the decision was made to revert the password change. So a discussion that might have led to a better understanding of how security-related decisions should be made within Fedora ended up, instead, with the possibility that the developer involved simply backed out the change rather than face the mob. That gives the Fedora community no guidance on either policy or the best way to handle technical disagreements; as such, it represents a missed opportunity. Passwords, arguably, should be invisible, but policy decisions usually belong in plain sight.

Comments (45 posted)

Miro 6, video, and the web

The Participatory Culture Foundation (PCF) released version 6.0 of its GPL-licensed desktop video application Miro in April. There are performance improvements and important new functionality, as one might expect. But Miro's development over the years also serves as a barometer for the state of online multimedia content—and the trend these days seems to be pulling away from RSS and other open standards.

For the benefit of the unfamiliar, Miro is a cross-platform GUI application designed to consolidate online audio and video sources into a single player that automatically handles subscriptions and other sources of recurring content. In the early days, it was named Democracy Player, and the emphasis was on managing RSS and Atom feeds for video sources, akin to a podcasting client for video. PCF's larger mission centers around promoting decentralized media creation and distribution; its other projects include Miro Community, a web platform for building video-sharing sites, the Amara framework for user-contributed video subtitles, and Miro Video Converter, a video conversion application (whose functionality is also available in Miro itself).

Over the years, support for additional means of content delivery have been added to Miro, including Bittorrent, web-based video sites (i.e., those that embed video content but do not produce a parsable feed), and dedicated services like Hulu. The application's interface resembles a desktop music player: content sources are listed in sidebar, with a collapsible tree grouping sources by type. Feed subscriptions are listed under "Podcasts," and Miro indicates the availability of new material with a numeric indicator next to the feed title. Each feed has separate settings regarding whether new items are automatically downloaded, how long they are retained, and so on.

Links to web video sites and digital music stores are each grouped in their own category, but Miro does not check either of these service types for new content automatically. The application can also manage a local music collection much like any other audio player. Oddly enough, although the music management feature allows users to browse by album and artist, the video management feature does not sport similar library-like options for managing a collection of local video files. Instead, it presents a sorted list and highlights entries that have not yet been watched—the emphasis is on watching what is new and moving on.

Feed me, see more

Miro is written primarily in Python, and the Linux version uses GStreamer for media playback and FFmpeg for format conversion. Although the earliest versions of the application focused on video feed management, an embedded browser engine has been available in Miro since the 1.0 release, allowing users to search for and bookmark video sites that do not produce a proper feed. Initially the engine was Gecko on all platforms, but starting with the 3.0 series in 2010, Miro has used WebKit on Linux.

By far the most noteworthy change in the 6.0 release is that it finally restores working Flash support on Linux (which had been broken since 2009), without which many of the web-based video services were unusable. However, Flash support is not an all-or-nothing proposition, and its value to the user depends on a number of variables.

The Linux version of 6.0 comes with a handful of well-known web video services (YouTube, Hulu, and PBS) pre-listed in the application's sidebar. Users can add their own by entering the URL, and the sidebar entries are essentially just browser bookmarks—nothing prevents one from loading up the sidebar with non-video sites (music services like Spotify, popular destinations like LWN.net, etc.). Flash videos do indeed play, although playback is dependent on having a Flash plugin by default. The official plugin, of course, is a proprietary binary blob, which not every Linux user will be thrilled with. The grim reality, however, is that avoiding the proprietary Flash plugin remains a process fraught with difficulty.

There are alternatives, albeit imperfect ones. If one visits the YouTube HTML5 trial page, for instance, one can switch on delivery of the HTML5 <video> element instead, and enjoy YouTube content in WebM or H.264 format instead. Getting to the trial page within Miro is not simple, unfortunately: one can only navigate to the URL directly by adding it as a sidebar entry (and the only other option is logging in to a registered YouTube account and changing the account settings). At present, however, YouTube remains one of the few video services that offers an HTML5 option. Ironically, it is also one of the only video sites supported by the other option: the open source Flash plugins Gnash and Lightspark.

In practice, visiting most Flash-driven video sites in Miro is little different than visiting them in Firefox or another browser. Since fewer and fewer services seem interested in distributing video over RSS or Atom, preferring instead to draw the user into their own little captive portals, offering a better-than-browser experience is a challenge that Miro will have to rise to meet. The application does do its best to parse content that does not come in standard feed form—for example, one can add a YouTube "channel" or search results page to the Podcasts sidebar, and Miro will attempt to pick out its video content and download it, but the results are unreliable. PCF also takes a firm stance against what is perceived as illegal activity: it will not allow the user to download videos embedded in a web page, nor is there any way to add a browser extension which adds such functionality.

Other than the long-awaited Flash fix on Linux, the 6.0 release of Miro is primarily a performance upgrade. Whether or not there are real-world speed gains can be hard to gauge, particularly on Linux where previous releases only handled feed-delivered video (where the speed of one's Internet connection is the biggest factor), but in my testing 6.0 is certainly no slower than it predecessors, and it is much less crash-prone. The side features, such as video conversion and portable device synchronization, have received updates as well, so they support newer phones and media codecs. Miro 6.0 also restores compatibility with the MythTV DVR platform; MythTV includes a tool called MiroBridge that treats Miro downloads as a virtual channel on a MythTV backend. MiroBridge broke on Linux during the Miro 4.x cycle, and PCF only implemented the fix for 6.0, skipping the 5.0 series altogether.

Although Miro does offer a smooth playback experience, it has its drawbacks, starting with the embedded browser. Much as there is no simple way to download a video from a web site in Miro's browser, there is no way to install an ad-blocking extension or tweak other settings. Thus, users for whom annoying web ads are usually a distant memory may be shocked by the sensory assault of giant, animated commercials plastered in every corner. There also appears to be no way to add music download stores that are not built-in by default (perhaps because PCF uses referral codes from store purchases as a means of fundraising).

Miro also grabs the first media file it finds from each podcast episode, which is not always desirable. Sometimes the user might prefer one of the "fallback" options, either due to the format (e.g., Theora instead of H.264) or due to file size (not everything must be seen in HD).

The $64,000 question: who cares?

Taken on its merits alone, Miro is a capable application. The integrated MiroGuide service run by PCF is an excellent way to find watchable and listenable content online amidst all the garbage, and Miro itself greatly simplifies managing and watching video (or audio) podcasts. Its player works well, offering full-screen functionality and a unified interface even for disparate sources. It even boasts simple format conversion and can synchronize portable devices. Watching video and listening to podcasts in Miro is a noticeably better experience than accessing the same material in the browser—just like reading blog content aggregated into a feed reader is noticeably better (for most people) than visiting the same blogs in the browser.

Nevertheless, Miro remains a comparatively little-known application, even among those who passionately mourn the impending demise of Google Reader. Perhaps the amount of content each reader consumes is part of the difference; I have 623 blog subscriptions at the moment, which dwarfs by several orders of magnitude the number of video and audio podcasts I have time for. On the other hand, video fanatics have plenty of other choices available, from set-top boxes like the Roku to open source media centers like MythTV or XBMC (which typically rely on third-party developers maintaining screen scraper code to extract video from web sites—which periodically break). Miro may simply be stuck in the middle: better than a browser (which gets the casual viewer by default), but less convenient than XBMC (which captures the obsessive viewer).

Miro's biggest obstacle, however, is something entirely beyond its control: the trend of commercial video sites to move away from RSS feed delivery towards self-contained, browser-only video. The trend is not technical in its motivations; businesses are rejecting feed-delivered video for financial reasons. But it still puts Miro in a difficult position. On a technical level, Miro for Linux may soon face yet another obstacle, since Adobe has decided to discontinue the NSAPI version of the Flash plugin for Linux. Perhaps switching to Chromium's embedded browser engine would help, perhaps Gnash and Lightspark will see renewed interest, or perhaps Mozilla's Shumway will make progress. But whatever happens, eventually a major shift will have to be made in order to retain Flash video playback on Linux. We are, of course, told that Flash is dying, but its longevity is legendary enough by now that few are willing to hold their breath and wait.

Miro may occupy a small niche, caught between the existing web browser experience on one hand and the media center experience on the other, but a small niche does not make a project unimportant. Miro's adeptness with video feed management is still unique; in comparison, the RSS feed support in XBMC and MythTV is awkward and second-class. The closest parallel is probably to audio podcasting clients like gPodder. To many users, the podcasting support in generic desktop audio players like Rhythmbox is good enough. But it isn't great, and gPodder still attracts plenty of users who prefer the first-class feed support. Miro's early release, too, proved that if you can do one thing and do it well, users will appreciate you. The restoration of Flash video support in 6.0 muddies the water a bit, but it does not detract from Miro's core strength.

Comments (3 posted)

LFCS: A $99 supercomputer

Parallel computing is at least part of the future of computing. When even fairly low-end phones have multiple cores, it is clear where things are headed. In the future, hardware with even more parallelism will be available, but parallel programming is not keeping up. Part of the problem there is the lack of availability of inexpensive, highly parallel hardware—which is exactly what Andreas Olofsson and his team at Adapteva have set out to address.

In his keynote at the 2013 Linux Foundation Collaboration Summit (LFCS), Olofsson described the Parallella—a $99 supercomputer that Adapteva ran a Kickstarter project to design and build. He began by noting that his keynote followed one from Samsung, which is the world's largest electronics company while he was representing "perhaps the smallest" electronics company. Olofsson is not only the CEO, he is also one-third of the engineering team, he said with a chuckle. Despite being so small, the company was able to build a 64-core 28nm chip that runs 100 GigaFLOPS at 2 watts.

Adapteva created that chip two years ago and went around the world trying to sell it, but that effort was met with "crickets", he said. The world just wasn't ready yet, so that's where the Kickstarter idea came from. Adapteva is turning into a systems company because "people want computers, they don't just want chips".

Energy efficiency has not kept up with Moore's law, which creates an "efficiency gap" that impacts both battery powered and plugged-in systems, he said. The gap has only started to widen in the last few years, which is why most people don't care—yet. But it is a problem that is getting worse and worse and will be quite severe by 2020 or 2025. We have to start thinking differently, he said.

The architecture that everyone wants is an infinitely fast single-threaded CPU with infinite memory and infinite bandwidth to that memory, which is, of course, impossible to have. We keep trying new things when we hit various limitations, scaling up the processor frequency, issuing multiple instructions per cycle, adding SIMD (single instruction, multiple data), and eventually adding more cores. "Now what?", he asked. We are "running out of tricks". We have seen this play out in servers and desktops, and are seeing it play out in mobile "as we speak".

When he started the company in 2008, there were a number of chip-design trends that he believed would shape the future of computing: things like power consumption, memory bottlenecks, thermal density, yield issues, software complexity, and Amdahl's law. But we have a very different example of computing that is close to hand: our brains. Whenever you look at the brain, you realize that what we have been designing is so primitive in comparison to what nature has already accomplished, he said. It is massively parallel (billions of neurons), energy efficient (30 watts), heterogeneous (different parts of the brain handle different functions), and robust (losing a small part generally does not shut the whole thing down).

The "practical vision" for today is heterogeneous, Olofsson said. We have system-on-chips (SoCs) that can combine different kinds of functional units, such as "big" CPUs, GPUs, and FPGAs. But, we won't see 1000 ARM cores on a single SoC, he said. What Adapteva has done is to add hundreds, or even thousands, of small RISC CPUs into a SoC with ARM or x86 cores as the main processor.

Programming

The current state of parallel programming is not up to the task of writing the code that will be needed for massively parallel systems of the future. The challenge is to make parallel programming as productive as Java or Python is today, Olofsson said. We should get to the point where GitHub has thousands of projects that are using parallel programming techniques that run on parallel hardware.

To get to this world of parallel ubiquity, the challenges are "immense". The computer ecosystem needs to be rebuilt. Billions of lines of code need to be rewritten, and millions of programmers need to be re-educated. In addition, the computer education curriculum needs to change so that people learn parallel programming in the first year of college—or even high school.

In his mind, there is no question that the future of computing is parallel; "how else are you going to scale?". Where else can you get the next million-times speedup, he asked. But there is a question of "when?" and it is "going to hurt before we get there". There is no reason not to start now, though, which is where some of the ideas behind Parallella come from.

Inspired by the Raspberry Pi, Parallella is a $99 credit-card-sized parallel computer. Adapteva is trying to create a market for its chip, but it is also "trying to do good at the same time". The only way to build up a good-sized community around a device like Parallella is to make it open, "which is hard for a hardware guy", he said. But that makes the platform accessible to interested hackers.

Parallella is cheap and easy to use, Olofsson said. He wishes Adapteva could sell a million of them (like Raspberry Pi), but thinks that's unlikely. If it sold 10,000 and people took them and did innovative things using Parallella, that would be a big success.

The Kickstarter tried to raise $750,000 in 30 days and was successful in doing so. He and his team have spent the last six months trying to deliver what had been promised. The goal was a 5 watt computer that could do 100GFLOPS, which was achieved. There are many different applications for such a device including software defined radio, ray tracing, image processing, robotics, cryptography, gaming, and more.

The system has a dual-core Cortex-A9 processor that runs Linux. It has most of the peripherals you would expect, but it also has a built-in FPGA. That device can be configured to "do anything" and is meant to augment the main processor. In addition, there is Adapteva's Epiphany co-processor, which brings many small RISC cores to the system.

At the time of the talk, it had only been five days since Adapteva had received the boards. Both 16-core and 64-core Epiphany versions were delivered (Olofsson is holding one of each in the photo above). Each consumes around 5 watts and he is "excited to get them in the hands of the right people". By the second day, the team could run "hello world" on the main CPU. Earlier in the day of the talk (day 5), he heard from another member of the team that it could talk to the Epiphany and run longer programs on the A9. Six months ago, he didn't know if you could actually build this type of system in credit card form factor with a $99 price point, but it can be done.

Now Adapteva needs to ship 6300 systems to people who donated to the Kickstarter, which is no easy task. There are some serious logistics to be worked out, because "we want people to be happy" with their boards. Adapteva also wants to give away free kits to universities. Building a sustainable distribution model with less than five people in the company will be challenging. It is running a little late, he said, but will be shipping all of the boards in the (northern hemisphere) summer.

Olofsson concluded with Adapteva's plans after all the shipping and handling: next up is "massive parallelism" with 1024-core Epiphany co-processors. It will be interesting to see what folks will do with that system when it becomes available.

Comments (19 posted)

Page editor: Jonathan Corbet

Inside this week's LWN.net Weekly Edition

• Security: IBM's homomorphic encryption library; New vulnerabilities in kernel, mesa, phpmyadmin, xen, ...
• Kernel: What's coming in 3.10, part 2; Full tickless; LLVMLinux.
• Distributions: Defining the Fedora user base; Debian, openSUSE Edu Li-f-e, ...
• Development: Glibc; Adobe's CFF rasterizer; Geary crowdfunding; spreading the word about your code; ...
• Announcements: OSI Board Changes, VP8 Patent Cross-license Agreement, Flock, ...