Kerneldebugstrategy – fedoraproject linux kernel network

Kerneldebugstrategy – fedoraproject linux kernel network Fedora enables differing amounts of debugging in the kernel at various times depending on where we are in the release cycle. During development, the rawhide/branched kernel typically always have the debug options enabled. Linux kernel maintainers The only exception to this, is that there is a non-debug build done for every -rc rebase. The linux kernel archives This build is not guaranteed to make it into the repo, as it may be obsoleted quickly by a subsequent debug build.

What is the kernel in linux (You can still get the non-debug build from koji). There are a couple of ways to tell which is a debug build and which isn’t before you install a kernel.

Linux kernel fundamentals The first is to look at the RPM changelog.


View kernel version linux If it says something like: * Mon Sep 17 2012 Josh Boyer – 3.6.0-0.rc6.git0.1 * Mon Sep 17 2012 Josh Boyer – 3.6.0-0.rc6.git0.2 then the build will be a debug kernel. Kernel linux The other way to tell is by looking in koji at the produced RPMs. Linux command kernel version If the build contains a kernel-debug- package, the default kernel- package is a non-debug kernel. If you want to know if your currently running kernel is a debug kernel or not, you can use the RPM changelog method still or you can look at the matching config file found in /boot. Download linux kernel source If it has CONFIG_DEBUG_SPINLOCK=y then it is a debug kernel. Compile kernel linux E.g.: [jwboyer@vader kernel]$ grep DEBUG_SPINLOCK /boot/config-3.6.0-0.rc4.git2.1.fc18.x86_64 [jwboyer@zod linux-2.6]$ grep DEBUG_SPINLOCK /boot/config-3.5.3-1.fc17.x86_64 is not. Linux kernel development tutorial The various DEBUG_ options can change depending on the kernel version, but DEBUG_SPINLOCK is a fairly good one to judge from. Linux kernel developers It will only be set on debug kernels. Alpha ships with the default kernel being a debug kernel. Linux kernel released At Beta we run ‘make release’ which creates the separate kernel-debug package in the build. Linux kernel 5 That remains the case for that branch going forward until the release EOL. If you want to use a non-debug kernel during early Fedora Branched stages (pre-Alpha), you can try to add a special Rawhide non-debug repository, see RawhideKernelNodebug. Linux kernel ebook It’s a Rawhide repository, so it might not work perfectly with Fedora Branched, but there’s a very high chance it will. Linux kernel upgrade After Fedora Branched switches to non-debug kernel by default (pre-Beta), just turn off this repository. • SPINLOCK_SLEEP (check if we’re in code where we can sleep before using locks) • DEBUG_SHIRQ (cause an interrupt to be generated as soon as we register an IRQ) • DEBUG_RODATA (write protect read-only data, cause a pagefault if something tries to write to it) • SLUB_DEBUG (perform a number of checks on allocated objects, poison free’d objects) • DEBUG_HIGHMEM (Allow debugging of highmem issues on non-highmem boxes) • DEBUG_MUTEXES DEBUG_RT_MUTEXES DEBUG_LOCK_ALLOC PROVE_LOCKING DEBUG_SPINLOCK (lock dependancy checker) There are also a number of other DEBUG options, which just add extra printk’s, or extra information in /proc or /sys, these are mostly uninteresting, and have little to no performance impact. Occasionally the Fedora kernel team may enable CONFIG_DEBUG_PAGEALLOC (after freeing an object, unmap it from the address space. Linux kernel driver Attempts to access it cause an oops). Linux kernel releases This option causes extreme performance loss, so is only enabled in rare cases when trying to track down bugs that have insufficient debugging data. ‘kernel’ and ‘kernel-PAE’ are deemed ‘performance’ kernels, and hence have no debugging options enabled which impact performance. Linux network kernel Several low impact options remain enabled, such as In addition, SLUB_DEBUG is enabled, but by default is inactive. Linux kernel introduction You need to boot with slub_debug=FPZU to make it perform its usual checks. How linux kernel works See Documentation/vm/slub.txt for more details about these options. The numerous lock dependancy checker options are enabled. Linux kernel nedir Most of the cost of this option is due to the size of spinlock/mutex structures increasing. Check kernel linux If embedded into other structures, these can blow up considerably. Linux kernel version history For performance critical structures like page struct (which normally fits in a cacheline), this can be expensive. Finally, the -debug kernels enable a bunch of fault-injection test modules. • CONFIG_DEBUG_IGNORE_QUIET is enabled, which makes the ‘quiet’ boot parameter ineffective. Schedule linux kernel This is done to ease debugging. • For the first alpha releases, DEBUG_PAGEALLOC is likely to be set, which is incredibly performance taxing. Linux kernel org It’s also known to cause problems on some virtual machines with buggy pagefault handlers. • Later alpha/beta releases disable PAGEALLOC in favour of relying on SLUB_DEBUG to catch similar bugs. How linux kernel works If obscure hard-to-debug issues occur later in the development cycle, PAGEALLOC may be re-enabled temporarily. Copyright © 2016 Red Hat, Inc. Building a linux kernel and others. Linux kernel smp All Rights Reserved. Linux kernel schedule For comments or queries, please contact us. The Fedora Project is maintained and driven by the community and sponsored by Red Hat. Linux kernel oops This is a community maintained site. Linux kernel list Red Hat is not responsible for content. • Content is available under Attribution-Share Alike 3.0 Unported unless otherwise noted. Site: https://fedoraproject.org/wiki/KernelDebugStrategy

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