apicmaintimer. Useful when your PIT timer is totally
broken.
+ disable_8254_timer / enable_8254_timer
+ Enable interrupt 0 timer routing over the 8254 in addition to over
+ the IO-APIC. The kernel tries to set a sensible default.
+
Early Console
syntax: earlyprintk=vga
pci=lastbus=NUMBER Scan upto NUMBER busses, no matter what the mptable says.
pci=noacpi Don't use ACPI to set up PCI interrupt routing.
-IOMMU
-
- iommu=[size][,noagp][,off][,force][,noforce][,leak][,memaper[=order]][,merge]
- [,forcesac][,fullflush][,nomerge][,noaperture][,calgary]
- size set size of iommu (in bytes)
- noagp don't initialize the AGP driver and use full aperture.
- off don't use the IOMMU
- leak turn on simple iommu leak tracing (only when CONFIG_IOMMU_LEAK is on)
- memaper[=order] allocate an own aperture over RAM with size 32MB^order.
- noforce don't force IOMMU usage. Default.
- force Force IOMMU.
- merge Do SG merging. Implies force (experimental)
- nomerge Don't do SG merging.
- forcesac For SAC mode for masks <40bits (experimental)
- fullflush Flush IOMMU on each allocation (default)
- nofullflush Don't use IOMMU fullflush
- allowed overwrite iommu off workarounds for specific chipsets.
- soft Use software bounce buffering (default for Intel machines)
- noaperture Don't touch the aperture for AGP.
- allowdac Allow DMA >4GB
- When off all DMA over >4GB is forced through an IOMMU or bounce
- buffering.
- nodac Forbid DMA >4GB
- panic Always panic when IOMMU overflows
- calgary Use the Calgary IOMMU if it is available
-
- swiotlb=pages[,force]
-
- pages Prereserve that many 128K pages for the software IO bounce buffering.
- force Force all IO through the software TLB.
-
- calgary=[64k,128k,256k,512k,1M,2M,4M,8M]
- calgary=[translate_empty_slots]
- calgary=[disable=<PCI bus number>]
+IOMMU (input/output memory management unit)
+
+ Currently four x86-64 PCI-DMA mapping implementations exist:
+
+ 1. <arch/x86_64/kernel/pci-nommu.c>: use no hardware/software IOMMU at all
+ (e.g. because you have < 3 GB memory).
+ Kernel boot message: "PCI-DMA: Disabling IOMMU"
+
+ 2. <arch/x86_64/kernel/pci-gart.c>: AMD GART based hardware IOMMU.
+ Kernel boot message: "PCI-DMA: using GART IOMMU"
+
+ 3. <arch/x86_64/kernel/pci-swiotlb.c> : Software IOMMU implementation. Used
+ e.g. if there is no hardware IOMMU in the system and it is need because
+ you have >3GB memory or told the kernel to us it (iommu=soft))
+ Kernel boot message: "PCI-DMA: Using software bounce buffering
+ for IO (SWIOTLB)"
+
+ 4. <arch/x86_64/pci-calgary.c> : IBM Calgary hardware IOMMU. Used in IBM
+ pSeries and xSeries servers. This hardware IOMMU supports DMA address
+ mapping with memory protection, etc.
+ Kernel boot message: "PCI-DMA: Using Calgary IOMMU"
+
+ iommu=[<size>][,noagp][,off][,force][,noforce][,leak[=<nr_of_leak_pages>]
+ [,memaper[=<order>]][,merge][,forcesac][,fullflush][,nomerge]
+ [,noaperture][,calgary]
+
+ General iommu options:
+ off Don't initialize and use any kind of IOMMU.
+ noforce Don't force hardware IOMMU usage when it is not needed.
+ (default).
+ force Force the use of the hardware IOMMU even when it is
+ not actually needed (e.g. because < 3 GB memory).
+ soft Use software bounce buffering (SWIOTLB) (default for
+ Intel machines). This can be used to prevent the usage
+ of an available hardware IOMMU.
+
+ iommu options only relevant to the AMD GART hardware IOMMU:
+ <size> Set the size of the remapping area in bytes.
+ allowed Overwrite iommu off workarounds for specific chipsets.
+ fullflush Flush IOMMU on each allocation (default).
+ nofullflush Don't use IOMMU fullflush.
+ leak Turn on simple iommu leak tracing (only when
+ CONFIG_IOMMU_LEAK is on). Default number of leak pages
+ is 20.
+ memaper[=<order>] Allocate an own aperture over RAM with size 32MB<<order.
+ (default: order=1, i.e. 64MB)
+ merge Do scatter-gather (SG) merging. Implies "force"
+ (experimental).
+ nomerge Don't do scatter-gather (SG) merging.
+ noaperture Ask the IOMMU not to touch the aperture for AGP.
+ forcesac Force single-address cycle (SAC) mode for masks <40bits
+ (experimental).
+ noagp Don't initialize the AGP driver and use full aperture.
+ allowdac Allow double-address cycle (DAC) mode, i.e. DMA >4GB.
+ DAC is used with 32-bit PCI to push a 64-bit address in
+ two cycles. When off all DMA over >4GB is forced through
+ an IOMMU or software bounce buffering.
+ nodac Forbid DAC mode, i.e. DMA >4GB.
+ panic Always panic when IOMMU overflows.
+ calgary Use the Calgary IOMMU if it is available
+
+ iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU
+ implementation:
+ swiotlb=<pages>[,force]
+ <pages> Prereserve that many 128K pages for the software IO
+ bounce buffering.
+ force Force all IO through the software TLB.
+
+ Settings for the IBM Calgary hardware IOMMU currently found in IBM
+ pSeries and xSeries machines:
+
+ calgary=[64k,128k,256k,512k,1M,2M,4M,8M]
+ calgary=[translate_empty_slots]
+ calgary=[disable=<PCI bus number>]
+ panic Always panic when IOMMU overflows
64k,...,8M - Set the size of each PCI slot's translation table
when using the Calgary IOMMU. This is the size of the translation
Debugging
- oops=panic Always panic on oopses. Default is to just kill the process,
- but there is a small probability of deadlocking the machine.
- This will also cause panics on machine check exceptions.
- Useful together with panic=30 to trigger a reboot.
+ oops=panic Always panic on oopses. Default is to just kill the process,
+ but there is a small probability of deadlocking the machine.
+ This will also cause panics on machine check exceptions.
+ Useful together with panic=30 to trigger a reboot.
- kstack=N Print that many words from the kernel stack in oops dumps.
+ kstack=N Print N words from the kernel stack in oops dumps.
- pagefaulttrace Dump all page faults. Only useful for extreme debugging
+ pagefaulttrace Dump all page faults. Only useful for extreme debugging
and will create a lot of output.
call_trace=[old|both|newfallback|new]
newfallback: use new unwinder but fall back to old if it gets
stuck (default)
- call_trace=[old|both|newfallback|new]
- old: use old inexact backtracer
- new: use new exact dwarf2 unwinder
- both: print entries from both
- newfallback: use new unwinder but fall back to old if it gets
- stuck (default)
-
-Misc
+Miscellaneous
noreplacement Don't replace instructions with more appropriate ones
for the CPU. This may be useful on asymmetric MP systems
- where some CPU have less capabilities than the others.
+ where some CPUs have less capabilities than others.
git.openpandora.org / pandora-kernel.git / blobdiff