|By Nicholas Petreley||
|February 11, 2002 12:00 AM EST||
(LinuxWorld) -- If you're not familiar with the kernel patch and development process, here it is in a nutshell. People modify source files to fix bugs, add or remove features, or adapt to changes in the way the kernel handles certain tasks. They produce patch files by using a utility called diff. diff compares the old source file to the new one and produces a text file from the differences. You can then distribute this text file to others, who can use it to patch their source code with the utility called (what else?) patch.
Incidentally, the tradition for using patch to produce kernel patch files is to add the command line switches
-urN, which tells diff to use the unified output format (which is what everyone on the kernel development team uses), recurse through directories, and keep track of new files that appear in one branch but not another. The full command would be
Until recently, kernel developers submitted their patch files by including them within the body of an email message. Then they sent the message to one or more kernel maintainers and/or the kernel development mailing list. I'm not quite sure how the patch submission process will change now that Linus Torvalds and others are using the Bitkeeper Web-based source management system, but it looks like they'll still rely largely on the diff
Linus or one of the other kernel maintainers merge the various patches into the kernel source tree, make other changes, and then release a collection of patches in one large text file, which is compressed for faster downloads. If you want to apply the patches, you download the file and apply it to the correct version of the kernel source code.
I don't know how others do this, but I keep kernel versions in directories like /usr/src/linux-2.4.18-pre8 to identify the kernel version for that source tree. Then I download the latest patches to the /usr/src directory. For example, I downloaded the Michael Cohen patch file patch-2.4.18-pre8-mjc.bz2 and put it in /usr/src. If I wanted to apply the Michael Cohen patch as is, I would then change to the /usr/src/linux-2.4.18-pre8 directory and run the command:
# bzcat ../patch-2.4.18-pre8-mjc.bz2 | patch -p1 -E --dry-run
Don't type the pound sign (#) - it's the part of the prompt that usually tells you you're logged in as the root user.
-p1 switch tells patch to ignore the first level of directories in the patch file. This can be important, because the maintainers all seem to use their own conventions for the root directory for the kernel source tree, and that directory name gets included in the patch file. For example, if someone keeps the old kernel source in /usr/src/oldkernel and the modified source in
/usr/src/newkernel, then the patch file will contain the two directory names oldkernel and newkernel. If you use the switch
-p0, patch will expect to find the newkernel directory name on your system as part of the full path name (for example, newkernel/drivers/ide/ide-dma.c). If, like me, you named the top directory of the kernel tree something like linux-2.4.18-pre8, patch will fail. The
-p1 switch tells it to ignore that top level and go straight to drivers/ide/ide-dma.c.
-E switch tells patch to go ahead and delete any files that shouldn't exist after the patch. These are generally files that the maintainer moved to another location or deleted because they were no longer needed.
The --dry-run portion of the command tells patch to pretend to apply the patches without actually changing anything. I do this out of habit because it prevents me from making stupid mistakes like changing to the wrong kernel tree before applying the patch. If the patch process produces many error messages, I know I've probably done something wrong. If it looks like everything patched ok, then I run the command again, only for real. That "for real" command is just the same command without the --dry-run:
# bzcat ../patch-2.4.18-pre8-mjc.bz2 | patch -p1 -E
The challengeThe 2.5 branch is still in too transitory a state to tackle with any confidence, so I started with linux-2.4.18-pre8. I figured I'd better take it slow. I've led a rather sedentary lifestyle when it comes to examining the kernel source, so I didn't want to break into a sprint on the first go and risk a heart attack. In other words, I wanted to merge only a handful of changes, not 50 at a shot the way Linus and others do.
I noticed that Michael Cohen had released a large patch against 2.4.18-pre8 that included many interesting features. It merges the code to handle hardware health sensors (so you can view things like the fan speed on your motherboard). It also adds code to make the kernel preemptive. It has other performance enhancing modifications to the kernel and includes several fixes that weren't in the 2.4 branch at the time Cohen posted his patch, such as fixes to the Reiserfs file system.
Thibaut Laurent posted on the kernel development mailing list that there was a minor problem with the file timer.c in Cohen's patch. Thomas Hood pointed out that Cohen's updates to the plug-and-play BIOS code were out of date. Paul P Komkoff Jr posted a set of patches that adds new capabilities for IP net filtering. Finally, I like to add a line to drivers/acpi/hardware/hwsleep.c to force the kernel to shut off the machine. This is not a patch for general use. I only include it because the funky ACPI BIOS tables in ASUS motherboards keep me from being able to shut off my system with the halt command.
I figured it would be a good lesson in patch management if I could apply all of the above fixes and additions to Michael Cohen's patch and produce my own patch from the result.
I downloaded the latest PnP BIOS code for 2.4.18-pre8 by Thomas Hood and began the grunt work of replacing the PnP portions of Cohen's patch with the latest code. The job was tedious, but it was easy because both Cohen's patch and Hood's patch are applied against the same kernel version (2.4.18-pre8). So all I really had to do was find all the sections of Cohen's patch that corresponded to Hood's and make the swap. It was even easier to apply the net filter additions, timer.c fix, and my shutdown kludge.
The result is patch-2.4.18-pre8-np.gz, which you can find at the download section of www.varlinux.org. I'm using that kernel right now, but things are moving so quickly it will probably be well out of date by the time you read this. There's already a linux-2.4.18-pre9 available as I write this and pre9 includes some of the same fixes you'll find in my patch. (It lacks all the added features, however, such as the net filter code, preemptive kernel, etc.)
What's the big deal about merging patches? It was only easy for me because I chose to work with a stable branch of the kernel and patches that were supposed to be applied against the same kernel version.
I tackled the 2.5.4-pre3 kernel source just to see what the differences would be like if I used an unstable branch. I didn't even have to look for patches to apply. It wouldn't compile on my system as is. It broke on ide-dma.c, ide-scsi.c, sg.c, and in other places. I couldn't find any fixes for these problems so I started scanning the code to see if I could fix it myself.
That's when I realized what this kernel development process really needs -- an editor with an integrated cross-reference and source code analysis system.
Perhaps people like Linus Torvalds doesn't need such a program because he knows where every instance of a variable appears in the source tree (I doubt it, since so many of his patches lately leave many files with legacy variables and structures unpatched to work with updates to other parts of the kernel source tree). Alternatively, perhaps he and others have some neat command-line utilities that do the job. I'm not an emacs user, so for all I know emacs has these capabilities (I have no idea if Linus uses emacs anyway).
However, I would want something more powerful than a multi-file editor for a job like this. So I searched Freshmeat and found a few snazzy products that analyze source code, cross reference the source, and let you perform recursive updates in ways that help prevent disaster. Some run on Linux, so I plan to play with one or two.
I'll get back to you on them when I've had time to learn how well they work. In the meantime, unless you're a kernel guru, stay away from the 2.5 branch. Stick to the easy stuff, like I do. Your heart will thank you for it.
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Aug. 2, 2015 05:45 PM EDT Reads: 509
For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space. In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...
Aug. 2, 2015 11:15 AM EDT Reads: 354
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Aug. 1, 2015 10:00 AM EDT Reads: 338
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
Jul. 30, 2015 07:30 PM EDT Reads: 1,421
MuleSoft has announced the findings of its 2015 Connectivity Benchmark Report on the adoption and business impact of APIs. The findings suggest traditional businesses are quickly evolving into "composable enterprises" built out of hundreds of connected software services, applications and devices. Most are embracing the Internet of Things (IoT) and microservices technologies like Docker. A majority are integrating wearables, like smart watches, and more than half plan to generate revenue with APIs within the next year.
Jul. 30, 2015 02:30 PM EDT Reads: 140
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Opening Keynote at 16th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, d...
Jul. 30, 2015 12:00 PM EDT Reads: 2,081
In his keynote at 16th Cloud Expo, Rodney Rogers, CEO of Virtustream, discussed the evolution of the company from inception to its recent acquisition by EMC – including personal insights, lessons learned (and some WTF moments) along the way. Learn how Virtustream’s unique approach of combining the economics and elasticity of the consumer cloud model with proper performance, application automation and security into a platform became a breakout success with enterprise customers and a natural fit for the EMC Federation.
Jul. 30, 2015 09:00 AM EDT Reads: 2,173
The Internet of Things is not only adding billions of sensors and billions of terabytes to the Internet. It is also forcing a fundamental change in the way we envision Information Technology. For the first time, more data is being created by devices at the edge of the Internet rather than from centralized systems. What does this mean for today's IT professional? In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists addressed this very serious issue of profound change in the industry.
Jul. 29, 2015 03:00 PM EDT Reads: 1,299
Discussions about cloud computing are evolving into discussions about enterprise IT in general. As enterprises increasingly migrate toward their own unique clouds, new issues such as the use of containers and microservices emerge to keep things interesting. In this Power Panel at 16th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the state of cloud computing today, and what enterprise IT professionals need to know about how the latest topics and trends affect their organization.
Jul. 29, 2015 02:00 PM EDT Reads: 1,206
It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society-changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed. In his session at @ThingsExpo, Jason Mondanaro, Director, Product Management at Metanga, discussed how you can plan to cooperate, partner, and form lasting all-star teams to change the world and it starts with business models and monetization strategies.
Jul. 28, 2015 04:30 PM EDT Reads: 1,776
Converging digital disruptions is creating a major sea change - Cisco calls this the Internet of Everything (IoE). IoE is the network connection of People, Process, Data and Things, fueled by Cloud, Mobile, Social, Analytics and Security, and it represents a $19Trillion value-at-stake over the next 10 years. In her keynote at @ThingsExpo, Manjula Talreja, VP of Cisco Consulting Services, discussed IoE and the enormous opportunities it provides to public and private firms alike. She will share what businesses must do to thrive in the IoE economy, citing examples from several industry sectors.
Jul. 28, 2015 11:00 AM EDT Reads: 2,049
There will be 150 billion connected devices by 2020. New digital businesses have already disrupted value chains across every industry. APIs are at the center of the digital business. You need to understand what assets you have that can be exposed digitally, what their digital value chain is, and how to create an effective business model around that value chain to compete in this economy. No enterprise can be complacent and not engage in the digital economy. Learn how to be the disruptor and not the disruptee.
Jul. 27, 2015 10:00 AM EDT Reads: 2,044
Akana has released Envision, an enhanced API analytics platform that helps enterprises mine critical insights across their digital eco-systems, understand their customers and partners and offer value-added personalized services. “In today’s digital economy, data-driven insights are proving to be a key differentiator for businesses. Understanding the data that is being tunneled through their APIs and how it can be used to optimize their business and operations is of paramount importance,” said Alistair Farquharson, CTO of Akana.
Jul. 27, 2015 09:00 AM EDT Reads: 335
Business as usual for IT is evolving into a "Make or Buy" decision on a service-by-service conversation with input from the LOBs. How does your organization move forward with cloud? In his general session at 16th Cloud Expo, Paul Maravei, Regional Sales Manager, Hybrid Cloud and Managed Services at Cisco, discusses how Cisco and its partners offer a market-leading portfolio and ecosystem of cloud infrastructure and application services that allow you to uniquely and securely combine cloud business applications and services across multiple cloud delivery models.
Jul. 27, 2015 08:00 AM EDT Reads: 1,910
The enterprise market will drive IoT device adoption over the next five years. In his session at @ThingsExpo, John Greenough, an analyst at BI Intelligence, division of Business Insider, analyzed how companies will adopt IoT products and the associated cost of adopting those products. John Greenough is the lead analyst covering the Internet of Things for BI Intelligence- Business Insider’s paid research service. Numerous IoT companies have cited his analysis of the IoT. Prior to joining BI Intelligence, he worked analyzing bank technology for Corporate Insight and The Clearing House Payment...
Jul. 26, 2015 09:00 PM EDT Reads: 1,588
"Optimal Design is a technology integration and product development firm that specializes in connecting devices to the cloud," stated Joe Wascow, Co-Founder & CMO of Optimal Design, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 25, 2015 02:00 PM EDT Reads: 404
SYS-CON Events announced today that CommVault has been named “Bronze Sponsor” of SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. A singular vision – a belief in a better way to address current and future data management needs – guides CommVault in the development of Singular Information Management® solutions for high-performance data protection, universal availability and simplified management of data on complex storage networks. CommVault's exclusive single-platform architecture gives companies unp...
Jul. 25, 2015 01:00 PM EDT Reads: 1,973
Electric Cloud and Arynga have announced a product integration partnership that will bring Continuous Delivery solutions to the automotive Internet-of-Things (IoT) market. The joint solution will help automotive manufacturers, OEMs and system integrators adopt DevOps automation and Continuous Delivery practices that reduce software build and release cycle times within the complex and specific parameters of embedded and IoT software systems.
Jul. 25, 2015 12:15 PM EDT Reads: 486
"ciqada is a combined platform of hardware modules and server products that lets people take their existing devices or new devices and lets them be accessible over the Internet for their users," noted Geoff Engelstein of ciqada, a division of Mars International, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.
Jul. 25, 2015 12:00 PM EDT Reads: 1,555
Internet of Things is moving from being a hype to a reality. Experts estimate that internet connected cars will grow to 152 million, while over 100 million internet connected wireless light bulbs and lamps will be operational by 2020. These and many other intriguing statistics highlight the importance of Internet powered devices and how market penetration is going to multiply many times over in the next few years.
Jul. 25, 2015 09:00 AM EDT Reads: 1,502