diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 59 |
1 files changed, 52 insertions, 7 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2b8ee90bb644..fd03e2b629bb 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -704,8 +704,11 @@ upon panic. This parameter reserves the physical memory region [offset, offset + size] for that kernel image. If '@offset' is omitted, then a suitable offset - is selected automatically. Check - Documentation/kdump/kdump.txt for further details. + is selected automatically. + [KNL, x86_64] select a region under 4G first, and + fall back to reserve region above 4G when '@offset' + hasn't been specified. + See Documentation/kdump/kdump.txt for further details. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory @@ -2544,6 +2547,40 @@ in the "bleeding edge" mini2440 support kernel at http://repo.or.cz/w/linux-2.6/mini2440.git + mitigations= + [X86,PPC,S390,ARM64] Control optional mitigations for + CPU vulnerabilities. This is a set of curated, + arch-independent options, each of which is an + aggregation of existing arch-specific options. + + off + Disable all optional CPU mitigations. This + improves system performance, but it may also + expose users to several CPU vulnerabilities. + Equivalent to: nopti [X86,PPC] + kpti=0 [ARM64] + nospectre_v1 [PPC] + nobp=0 [S390] + nospectre_v2 [X86,PPC,S390,ARM64] + spectre_v2_user=off [X86] + spec_store_bypass_disable=off [X86,PPC] + ssbd=force-off [ARM64] + l1tf=off [X86] + + auto (default) + Mitigate all CPU vulnerabilities, but leave SMT + enabled, even if it's vulnerable. This is for + users who don't want to be surprised by SMT + getting disabled across kernel upgrades, or who + have other ways of avoiding SMT-based attacks. + Equivalent to: (default behavior) + + auto,nosmt + Mitigate all CPU vulnerabilities, disabling SMT + if needed. This is for users who always want to + be fully mitigated, even if it means losing SMT. + Equivalent to: l1tf=flush,nosmt [X86] + mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this parameter allows control of the logging verbosity for @@ -2873,10 +2910,10 @@ check bypass). With this option data leaks are possible in the system. - nospectre_v2 [X86,PPC_FSL_BOOK3E] Disable all mitigations for the Spectre variant 2 - (indirect branch prediction) vulnerability. System may - allow data leaks with this option, which is equivalent - to spectre_v2=off. + nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for + the Spectre variant 2 (indirect branch prediction) + vulnerability. System may allow data leaks with this + option. nospec_store_bypass_disable [HW] Disable all mitigations for the Speculative Store Bypass vulnerability @@ -3394,6 +3431,8 @@ bridges without forcing it upstream. Note: this removes isolation between devices and may put more devices in an IOMMU group. + force_floating [S390] Force usage of floating interrupts. + nomio [S390] Do not use MIO instructions. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. @@ -3623,7 +3662,9 @@ see CONFIG_RAS_CEC help text. rcu_nocbs= [KNL] - The argument is a cpu list, as described above. + The argument is a cpu list, as described above, + except that the string "all" can be used to + specify every CPU on the system. In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. @@ -4703,6 +4744,10 @@ [x86] unstable: mark the TSC clocksource as unstable, this marks the TSC unconditionally unstable at bootup and avoids any further wobbles once the TSC watchdog notices. + [x86] nowatchdog: disable clocksource watchdog. Used + in situations with strict latency requirements (where + interruptions from clocksource watchdog are not + acceptable). turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface |