included in this merge do the following: - Kemeng Shi has contributed some compation maintenance work in the series "Fixes and cleanups to compaction". - Joel Fernandes has a patchset ("Optimize mremap during mutual alignment within PMD") which fixes an obscure issue with mremap()'s pagetable handling during a subsequent exec(), based upon an implementation which Linus suggested. - More DAMON/DAMOS maintenance and feature work from SeongJae Park i the following patch series: mm/damon: misc fixups for documents, comments and its tracepoint mm/damon: add a tracepoint for damos apply target regions mm/damon: provide pseudo-moving sum based access rate mm/damon: implement DAMOS apply intervals mm/damon/core-test: Fix memory leaks in core-test mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval - In the series "Do not try to access unaccepted memory" Adrian Hunter provides some fixups for the recently-added "unaccepted memory' feature. To increase the feature's checking coverage. "Plug a few gaps where RAM is exposed without checking if it is unaccepted memory". - In the series "cleanups for lockless slab shrink" Qi Zheng has done some maintenance work which is preparation for the lockless slab shrinking code. - Qi Zheng has redone the earlier (and reverted) attempt to make slab shrinking lockless in the series "use refcount+RCU method to implement lockless slab shrink". - David Hildenbrand contributes some maintenance work for the rmap code in the series "Anon rmap cleanups". - Kefeng Wang does more folio conversions and some maintenance work in the migration code. Series "mm: migrate: more folio conversion and unification". - Matthew Wilcox has fixed an issue in the buffer_head code which was causing long stalls under some heavy memory/IO loads. Some cleanups were added on the way. Series "Add and use bdev_getblk()". - In the series "Use nth_page() in place of direct struct page manipulation" Zi Yan has fixed a potential issue with the direct manipulation of hugetlb page frames. - In the series "mm: hugetlb: Skip initialization of gigantic tail struct pages if freed by HVO" has improved our handling of gigantic pages in the hugetlb vmmemmep optimizaton code. This provides significant boot time improvements when significant amounts of gigantic pages are in use. - Matthew Wilcox has sent the series "Small hugetlb cleanups" - code rationalization and folio conversions in the hugetlb code. - Yin Fengwei has improved mlock()'s handling of large folios in the series "support large folio for mlock" - In the series "Expose swapcache stat for memcg v1" Liu Shixin has added statistics for memcg v1 users which are available (and useful) under memcg v2. - Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable) prctl so that userspace may direct the kernel to not automatically propagate the denial to child processes. The series is named "MDWE without inheritance". - Kefeng Wang has provided the series "mm: convert numa balancing functions to use a folio" which does what it says. - In the series "mm/ksm: add fork-exec support for prctl" Stefan Roesch makes is possible for a process to propagate KSM treatment across exec(). - Huang Ying has enhanced memory tiering's calculation of memory distances. This is used to permit the dax/kmem driver to use "high bandwidth memory" in addition to Optane Data Center Persistent Memory Modules (DCPMM). The series is named "memory tiering: calculate abstract distance based on ACPI HMAT" - In the series "Smart scanning mode for KSM" Stefan Roesch has optimized KSM by teaching it to retain and use some historical information from previous scans. - Yosry Ahmed has fixed some inconsistencies in memcg statistics in the series "mm: memcg: fix tracking of pending stats updates values". - In the series "Implement IOCTL to get and optionally clear info about PTEs" Peter Xu has added an ioctl to /proc/<pid>/pagemap which permits us to atomically read-then-clear page softdirty state. This is mainly used by CRIU. - Hugh Dickins contributed the series "shmem,tmpfs: general maintenance" - a bunch of relatively minor maintenance tweaks to this code. - Matthew Wilcox has increased the use of the VMA lock over file-backed page faults in the series "Handle more faults under the VMA lock". Some rationalizations of the fault path became possible as a result. - In the series "mm/rmap: convert page_move_anon_rmap() to folio_move_anon_rmap()" David Hildenbrand has implemented some cleanups and folio conversions. - In the series "various improvements to the GUP interface" Lorenzo Stoakes has simplified and improved the GUP interface with an eye to providing groundwork for future improvements. - Andrey Konovalov has sent along the series "kasan: assorted fixes and improvements" which does those things. - Some page allocator maintenance work from Kemeng Shi in the series "Two minor cleanups to break_down_buddy_pages". - In thes series "New selftest for mm" Breno Leitao has developed another MM self test which tickles a race we had between madvise() and page faults. - In the series "Add folio_end_read" Matthew Wilcox provides cleanups and an optimization to the core pagecache code. - Nhat Pham has added memcg accounting for hugetlb memory in the series "hugetlb memcg accounting". - Cleanups and rationalizations to the pagemap code from Lorenzo Stoakes, in the series "Abstract vma_merge() and split_vma()". - Audra Mitchell has fixed issues in the procfs page_owner code's new timestamping feature which was causing some misbehaviours. In the series "Fix page_owner's use of free timestamps". - Lorenzo Stoakes has fixed the handling of new mappings of sealed files in the series "permit write-sealed memfd read-only shared mappings". - Mike Kravetz has optimized the hugetlb vmemmap optimization in the series "Batch hugetlb vmemmap modification operations". - Some buffer_head folio conversions and cleanups from Matthew Wilcox in the series "Finish the create_empty_buffers() transition". - As a page allocator performance optimization Huang Ying has added automatic tuning to the allocator's per-cpu-pages feature, in the series "mm: PCP high auto-tuning". - Roman Gushchin has contributed the patchset "mm: improve performance of accounted kernel memory allocations" which improves their performance by ~30% as measured by a micro-benchmark. - folio conversions from Kefeng Wang in the series "mm: convert page cpupid functions to folios". - Some kmemleak fixups in Liu Shixin's series "Some bugfix about kmemleak". - Qi Zheng has improved our handling of memoryless nodes by keeping them off the allocation fallback list. This is done in the series "handle memoryless nodes more appropriately". - khugepaged conversions from Vishal Moola in the series "Some khugepaged folio conversions". -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCZULEMwAKCRDdBJ7gKXxA jhQHAQCYpD3g849x69DmHnHWHm/EHQLvQmRMDeYZI+nx/sCJOwEAw4AKg0Oemv9y FgeUPAD1oasg6CP+INZvCj34waNxwAc= =E+Y4 -----END PGP SIGNATURE----- Merge tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: "Many singleton patches against the MM code. The patch series which are included in this merge do the following: - Kemeng Shi has contributed some compation maintenance work in the series 'Fixes and cleanups to compaction' - Joel Fernandes has a patchset ('Optimize mremap during mutual alignment within PMD') which fixes an obscure issue with mremap()'s pagetable handling during a subsequent exec(), based upon an implementation which Linus suggested - More DAMON/DAMOS maintenance and feature work from SeongJae Park i the following patch series: mm/damon: misc fixups for documents, comments and its tracepoint mm/damon: add a tracepoint for damos apply target regions mm/damon: provide pseudo-moving sum based access rate mm/damon: implement DAMOS apply intervals mm/damon/core-test: Fix memory leaks in core-test mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval - In the series 'Do not try to access unaccepted memory' Adrian Hunter provides some fixups for the recently-added 'unaccepted memory' feature. To increase the feature's checking coverage. 'Plug a few gaps where RAM is exposed without checking if it is unaccepted memory' - In the series 'cleanups for lockless slab shrink' Qi Zheng has done some maintenance work which is preparation for the lockless slab shrinking code - Qi Zheng has redone the earlier (and reverted) attempt to make slab shrinking lockless in the series 'use refcount+RCU method to implement lockless slab shrink' - David Hildenbrand contributes some maintenance work for the rmap code in the series 'Anon rmap cleanups' - Kefeng Wang does more folio conversions and some maintenance work in the migration code. Series 'mm: migrate: more folio conversion and unification' - Matthew Wilcox has fixed an issue in the buffer_head code which was causing long stalls under some heavy memory/IO loads. Some cleanups were added on the way. Series 'Add and use bdev_getblk()' - In the series 'Use nth_page() in place of direct struct page manipulation' Zi Yan has fixed a potential issue with the direct manipulation of hugetlb page frames - In the series 'mm: hugetlb: Skip initialization of gigantic tail struct pages if freed by HVO' has improved our handling of gigantic pages in the hugetlb vmmemmep optimizaton code. This provides significant boot time improvements when significant amounts of gigantic pages are in use - Matthew Wilcox has sent the series 'Small hugetlb cleanups' - code rationalization and folio conversions in the hugetlb code - Yin Fengwei has improved mlock()'s handling of large folios in the series 'support large folio for mlock' - In the series 'Expose swapcache stat for memcg v1' Liu Shixin has added statistics for memcg v1 users which are available (and useful) under memcg v2 - Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable) prctl so that userspace may direct the kernel to not automatically propagate the denial to child processes. The series is named 'MDWE without inheritance' - Kefeng Wang has provided the series 'mm: convert numa balancing functions to use a folio' which does what it says - In the series 'mm/ksm: add fork-exec support for prctl' Stefan Roesch makes is possible for a process to propagate KSM treatment across exec() - Huang Ying has enhanced memory tiering's calculation of memory distances. This is used to permit the dax/kmem driver to use 'high bandwidth memory' in addition to Optane Data Center Persistent Memory Modules (DCPMM). The series is named 'memory tiering: calculate abstract distance based on ACPI HMAT' - In the series 'Smart scanning mode for KSM' Stefan Roesch has optimized KSM by teaching it to retain and use some historical information from previous scans - Yosry Ahmed has fixed some inconsistencies in memcg statistics in the series 'mm: memcg: fix tracking of pending stats updates values' - In the series 'Implement IOCTL to get and optionally clear info about PTEs' Peter Xu has added an ioctl to /proc/<pid>/pagemap which permits us to atomically read-then-clear page softdirty state. This is mainly used by CRIU - Hugh Dickins contributed the series 'shmem,tmpfs: general maintenance', a bunch of relatively minor maintenance tweaks to this code - Matthew Wilcox has increased the use of the VMA lock over file-backed page faults in the series 'Handle more faults under the VMA lock'. Some rationalizations of the fault path became possible as a result - In the series 'mm/rmap: convert page_move_anon_rmap() to folio_move_anon_rmap()' David Hildenbrand has implemented some cleanups and folio conversions - In the series 'various improvements to the GUP interface' Lorenzo Stoakes has simplified and improved the GUP interface with an eye to providing groundwork for future improvements - Andrey Konovalov has sent along the series 'kasan: assorted fixes and improvements' which does those things - Some page allocator maintenance work from Kemeng Shi in the series 'Two minor cleanups to break_down_buddy_pages' - In thes series 'New selftest for mm' Breno Leitao has developed another MM self test which tickles a race we had between madvise() and page faults - In the series 'Add folio_end_read' Matthew Wilcox provides cleanups and an optimization to the core pagecache code - Nhat Pham has added memcg accounting for hugetlb memory in the series 'hugetlb memcg accounting' - Cleanups and rationalizations to the pagemap code from Lorenzo Stoakes, in the series 'Abstract vma_merge() and split_vma()' - Audra Mitchell has fixed issues in the procfs page_owner code's new timestamping feature which was causing some misbehaviours. In the series 'Fix page_owner's use of free timestamps' - Lorenzo Stoakes has fixed the handling of new mappings of sealed files in the series 'permit write-sealed memfd read-only shared mappings' - Mike Kravetz has optimized the hugetlb vmemmap optimization in the series 'Batch hugetlb vmemmap modification operations' - Some buffer_head folio conversions and cleanups from Matthew Wilcox in the series 'Finish the create_empty_buffers() transition' - As a page allocator performance optimization Huang Ying has added automatic tuning to the allocator's per-cpu-pages feature, in the series 'mm: PCP high auto-tuning' - Roman Gushchin has contributed the patchset 'mm: improve performance of accounted kernel memory allocations' which improves their performance by ~30% as measured by a micro-benchmark - folio conversions from Kefeng Wang in the series 'mm: convert page cpupid functions to folios' - Some kmemleak fixups in Liu Shixin's series 'Some bugfix about kmemleak' - Qi Zheng has improved our handling of memoryless nodes by keeping them off the allocation fallback list. This is done in the series 'handle memoryless nodes more appropriately' - khugepaged conversions from Vishal Moola in the series 'Some khugepaged folio conversions'" [ bcachefs conflicts with the dynamically allocated shrinkers have been resolved as per Stephen Rothwell in https://lore.kernel.org/all/20230913093553.4290421e@canb.auug.org.au/ with help from Qi Zheng. The clone3 test filtering conflict was half-arsed by yours truly ] * tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (406 commits) mm/damon/sysfs: update monitoring target regions for online input commit mm/damon/sysfs: remove requested targets when online-commit inputs selftests: add a sanity check for zswap Documentation: maple_tree: fix word spelling error mm/vmalloc: fix the unchecked dereference warning in vread_iter() zswap: export compression failure stats Documentation: ubsan: drop "the" from article title mempolicy: migration attempt to match interleave nodes mempolicy: mmap_lock is not needed while migrating folios mempolicy: alloc_pages_mpol() for NUMA policy without vma mm: add page_rmappable_folio() wrapper mempolicy: remove confusing MPOL_MF_LAZY dead code mempolicy: mpol_shared_policy_init() without pseudo-vma mempolicy trivia: use pgoff_t in shared mempolicy tree mempolicy trivia: slightly more consistent naming mempolicy trivia: delete those ancient pr_debug()s mempolicy: fix migrate_pages(2) syscall return nr_failed kernfs: drop shared NUMA mempolicy hooks hugetlbfs: drop shared NUMA mempolicy pretence mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets() ... |
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acpi | ||
aoe | ||
auxdisplay | ||
blockdev | ||
cgroup-v1 | ||
cifs | ||
device-mapper | ||
gpio | ||
hw-vuln | ||
kdump | ||
laptops | ||
LSM | ||
media | ||
mm | ||
namespaces | ||
nfs | ||
perf | ||
pm | ||
sysctl | ||
thermal | ||
abi-obsolete.rst | ||
abi-removed.rst | ||
abi-stable.rst | ||
abi-testing.rst | ||
abi.rst | ||
bcache.rst | ||
binderfs.rst | ||
binfmt-misc.rst | ||
bootconfig.rst | ||
braille-console.rst | ||
btmrvl.rst | ||
bug-bisect.rst | ||
bug-hunting.rst | ||
cgroup-v2.rst | ||
clearing-warn-once.rst | ||
cpu-load.rst | ||
cputopology.rst | ||
dell_rbu.rst | ||
devices.rst | ||
devices.txt | ||
dynamic-debug-howto.rst | ||
edid.rst | ||
efi-stub.rst | ||
ext4.rst | ||
features.rst | ||
filesystem-monitoring.rst | ||
highuid.rst | ||
hw_random.rst | ||
index.rst | ||
init.rst | ||
initrd.rst | ||
iostats.rst | ||
java.rst | ||
jfs.rst | ||
kernel-parameters.rst | ||
kernel-parameters.txt | ||
kernel-per-CPU-kthreads.rst | ||
lcd-panel-cgram.rst | ||
ldm.rst | ||
lockup-watchdogs.rst | ||
md.rst | ||
module-signing.rst | ||
mono.rst | ||
numastat.rst | ||
parport.rst | ||
perf-security.rst | ||
pnp.rst | ||
pstore-blk.rst | ||
quickly-build-trimmed-linux.rst | ||
ramoops.rst | ||
rapidio.rst | ||
ras.rst | ||
README.rst | ||
reporting-issues.rst | ||
reporting-regressions.rst | ||
rtc.rst | ||
serial-console.rst | ||
spkguide.txt | ||
svga.rst | ||
syscall-user-dispatch.rst | ||
sysfs-rules.rst | ||
sysrq.rst | ||
tainted-kernels.rst | ||
thunderbolt.rst | ||
ufs.rst | ||
unicode.rst | ||
vga-softcursor.rst | ||
video-output.rst | ||
workload-tracing.rst | ||
xfs.rst |
.. _readme: Linux kernel release 6.x <http://kernel.org/> ============================================= These are the release notes for Linux version 6. Read them carefully, as they tell you what this is all about, explain how to install the kernel, and what to do if something goes wrong. What is Linux? -------------- Linux is a clone of the operating system Unix, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance. It has all the features you would expect in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management, and multistack networking including IPv4 and IPv6. It is distributed under the GNU General Public License v2 - see the accompanying COPYING file for more details. On what hardware does it run? ----------------------------- Although originally developed first for 32-bit x86-based PCs (386 or higher), today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell, IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64 Xtensa, and ARC architectures. Linux is easily portable to most general-purpose 32- or 64-bit architectures as long as they have a paged memory management unit (PMMU) and a port of the GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has also been ported to a number of architectures without a PMMU, although functionality is then obviously somewhat limited. Linux has also been ported to itself. You can now run the kernel as a userspace application - this is called UserMode Linux (UML). Documentation ------------- - There is a lot of documentation available both in electronic form on the Internet and in books, both Linux-specific and pertaining to general UNIX questions. I'd recommend looking into the documentation subdirectories on any Linux FTP site for the LDP (Linux Documentation Project) books. This README is not meant to be documentation on the system: there are much better sources available. - There are various README files in the Documentation/ subdirectory: these typically contain kernel-specific installation notes for some drivers for example. Please read the :ref:`Documentation/process/changes.rst <changes>` file, as it contains information about the problems, which may result by upgrading your kernel. Installing the kernel source ---------------------------- - If you install the full sources, put the kernel tarball in a directory where you have permissions (e.g. your home directory) and unpack it:: xz -cd linux-6.x.tar.xz | tar xvf - Replace "X" with the version number of the latest kernel. Do NOT use the /usr/src/linux area! This area has a (usually incomplete) set of kernel headers that are used by the library header files. They should match the library, and not get messed up by whatever the kernel-du-jour happens to be. - You can also upgrade between 6.x releases by patching. Patches are distributed in the xz format. To install by patching, get all the newer patch files, enter the top level directory of the kernel source (linux-6.x) and execute:: xz -cd ../patch-6.x.xz | patch -p1 Replace "x" for all versions bigger than the version "x" of your current source tree, **in_order**, and you should be ok. You may want to remove the backup files (some-file-name~ or some-file-name.orig), and make sure that there are no failed patches (some-file-name# or some-file-name.rej). If there are, either you or I have made a mistake. Unlike patches for the 6.x kernels, patches for the 6.x.y kernels (also known as the -stable kernels) are not incremental but instead apply directly to the base 6.x kernel. For example, if your base kernel is 6.0 and you want to apply the 6.0.3 patch, you must not first apply the 6.0.1 and 6.0.2 patches. Similarly, if you are running kernel version 6.0.2 and want to jump to 6.0.3, you must first reverse the 6.0.2 patch (that is, patch -R) **before** applying the 6.0.3 patch. You can read more on this in :ref:`Documentation/process/applying-patches.rst <applying_patches>`. Alternatively, the script patch-kernel can be used to automate this process. It determines the current kernel version and applies any patches found:: linux/scripts/patch-kernel linux The first argument in the command above is the location of the kernel source. Patches are applied from the current directory, but an alternative directory can be specified as the second argument. - Make sure you have no stale .o files and dependencies lying around:: cd linux make mrproper You should now have the sources correctly installed. Software requirements --------------------- Compiling and running the 6.x kernels requires up-to-date versions of various software packages. Consult :ref:`Documentation/process/changes.rst <changes>` for the minimum version numbers required and how to get updates for these packages. Beware that using excessively old versions of these packages can cause indirect errors that are very difficult to track down, so don't assume that you can just update packages when obvious problems arise during build or operation. Build directory for the kernel ------------------------------ When compiling the kernel, all output files will per default be stored together with the kernel source code. Using the option ``make O=output/dir`` allows you to specify an alternate place for the output files (including .config). Example:: kernel source code: /usr/src/linux-6.x build directory: /home/name/build/kernel To configure and build the kernel, use:: cd /usr/src/linux-6.x make O=/home/name/build/kernel menuconfig make O=/home/name/build/kernel sudo make O=/home/name/build/kernel modules_install install Please note: If the ``O=output/dir`` option is used, then it must be used for all invocations of make. Configuring the kernel ---------------------- Do not skip this step even if you are only upgrading one minor version. New configuration options are added in each release, and odd problems will turn up if the configuration files are not set up as expected. If you want to carry your existing configuration to a new version with minimal work, use ``make oldconfig``, which will only ask you for the answers to new questions. - Alternative configuration commands are:: "make config" Plain text interface. "make menuconfig" Text based color menus, radiolists & dialogs. "make nconfig" Enhanced text based color menus. "make xconfig" Qt based configuration tool. "make gconfig" GTK+ based configuration tool. "make oldconfig" Default all questions based on the contents of your existing ./.config file and asking about new config symbols. "make olddefconfig" Like above, but sets new symbols to their default values without prompting. "make defconfig" Create a ./.config file by using the default symbol values from either arch/$ARCH/defconfig or arch/$ARCH/configs/${PLATFORM}_defconfig, depending on the architecture. "make ${PLATFORM}_defconfig" Create a ./.config file by using the default symbol values from arch/$ARCH/configs/${PLATFORM}_defconfig. Use "make help" to get a list of all available platforms of your architecture. "make allyesconfig" Create a ./.config file by setting symbol values to 'y' as much as possible. "make allmodconfig" Create a ./.config file by setting symbol values to 'm' as much as possible. "make allnoconfig" Create a ./.config file by setting symbol values to 'n' as much as possible. "make randconfig" Create a ./.config file by setting symbol values to random values. "make localmodconfig" Create a config based on current config and loaded modules (lsmod). Disables any module option that is not needed for the loaded modules. To create a localmodconfig for another machine, store the lsmod of that machine into a file and pass it in as a LSMOD parameter. Also, you can preserve modules in certain folders or kconfig files by specifying their paths in parameter LMC_KEEP. target$ lsmod > /tmp/mylsmod target$ scp /tmp/mylsmod host:/tmp host$ make LSMOD=/tmp/mylsmod \ LMC_KEEP="drivers/usb:drivers/gpu:fs" \ localmodconfig The above also works when cross compiling. "make localyesconfig" Similar to localmodconfig, except it will convert all module options to built in (=y) options. You can also preserve modules by LMC_KEEP. "make kvm_guest.config" Enable additional options for kvm guest kernel support. "make xen.config" Enable additional options for xen dom0 guest kernel support. "make tinyconfig" Configure the tiniest possible kernel. You can find more information on using the Linux kernel config tools in Documentation/kbuild/kconfig.rst. - NOTES on ``make config``: - Having unnecessary drivers will make the kernel bigger, and can under some circumstances lead to problems: probing for a nonexistent controller card may confuse your other controllers. - A kernel with math-emulation compiled in will still use the coprocessor if one is present: the math emulation will just never get used in that case. The kernel will be slightly larger, but will work on different machines regardless of whether they have a math coprocessor or not. - The "kernel hacking" configuration details usually result in a bigger or slower kernel (or both), and can even make the kernel less stable by configuring some routines to actively try to break bad code to find kernel problems (kmalloc()). Thus you should probably answer 'n' to the questions for "development", "experimental", or "debugging" features. Compiling the kernel -------------------- - Make sure you have at least gcc 5.1 available. For more information, refer to :ref:`Documentation/process/changes.rst <changes>`. - Do a ``make`` to create a compressed kernel image. It is also possible to do ``make install`` if you have lilo installed to suit the kernel makefiles, but you may want to check your particular lilo setup first. To do the actual install, you have to be root, but none of the normal build should require that. Don't take the name of root in vain. - If you configured any of the parts of the kernel as ``modules``, you will also have to do ``make modules_install``. - Verbose kernel compile/build output: Normally, the kernel build system runs in a fairly quiet mode (but not totally silent). However, sometimes you or other kernel developers need to see compile, link, or other commands exactly as they are executed. For this, use "verbose" build mode. This is done by passing ``V=1`` to the ``make`` command, e.g.:: make V=1 all To have the build system also tell the reason for the rebuild of each target, use ``V=2``. The default is ``V=0``. - Keep a backup kernel handy in case something goes wrong. This is especially true for the development releases, since each new release contains new code which has not been debugged. Make sure you keep a backup of the modules corresponding to that kernel, as well. If you are installing a new kernel with the same version number as your working kernel, make a backup of your modules directory before you do a ``make modules_install``. Alternatively, before compiling, use the kernel config option "LOCALVERSION" to append a unique suffix to the regular kernel version. LOCALVERSION can be set in the "General Setup" menu. - In order to boot your new kernel, you'll need to copy the kernel image (e.g. .../linux/arch/x86/boot/bzImage after compilation) to the place where your regular bootable kernel is found. - Booting a kernel directly from a floppy without the assistance of a bootloader such as LILO, is no longer supported. If you boot Linux from the hard drive, chances are you use LILO, which uses the kernel image as specified in the file /etc/lilo.conf. The kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or /boot/bzImage. To use the new kernel, save a copy of the old image and copy the new image over the old one. Then, you MUST RERUN LILO to update the loading map! If you don't, you won't be able to boot the new kernel image. Reinstalling LILO is usually a matter of running /sbin/lilo. You may wish to edit /etc/lilo.conf to specify an entry for your old kernel image (say, /vmlinux.old) in case the new one does not work. See the LILO docs for more information. After reinstalling LILO, you should be all set. Shutdown the system, reboot, and enjoy! If you ever need to change the default root device, video mode, etc. in the kernel image, use your bootloader's boot options where appropriate. No need to recompile the kernel to change these parameters. - Reboot with the new kernel and enjoy. If something goes wrong ----------------------- If you have problems that seem to be due to kernel bugs, please follow the instructions at 'Documentation/admin-guide/reporting-issues.rst'. Hints on understanding kernel bug reports are in 'Documentation/admin-guide/bug-hunting.rst'. More on debugging the kernel with gdb is in 'Documentation/dev-tools/gdb-kernel-debugging.rst' and 'Documentation/dev-tools/kgdb.rst'.