Merge remote-tracking branch 'tip/auto-latest'

[deliverable/linux.git] / Documentation / kernel-parameters.txt

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 3725976d0af52311548f60acc6f6d6ac606b5675..b28015cad949571408b4e544dc1d1588be9d4a8f 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -460,6 +460,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        driver will print ACPI tables for AMD IOMMU during
                        IOMMU initialization.
 
+       amd_iommu_intr= [HW,X86-64]
+                       Specifies one of the following AMD IOMMU interrupt
+                       remapping modes:
+                       legacy     - Use legacy interrupt remapping mode.
+                       vapic      - Use virtual APIC mode, which allows IOMMU
+                                    to inject interrupts directly into guest.
+                                    This mode requires kvm-amd.avic=1.
+                                    (Default when IOMMU HW support is present.)
+
        amijoy.map=     [HW,JOY] Amiga joystick support
                        Map of devices attached to JOY0DAT and JOY1DAT
                        Format: <a>,<b>
@@ -1693,7 +1702,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
        intel_idle.max_cstate=  [KNL,HW,ACPI,X86]
                        0       disables intel_idle and fall back on acpi_idle.
-                       1 to 6  specify maximum depth of C-state.
+                       1 to 9  specify maximum depth of C-state.
 
        intel_pstate=  [X86]
                       disable
@@ -2166,10 +2175,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        than or equal to this physical address is ignored.
 
        maxcpus=        [SMP] Maximum number of processors that an SMP kernel
-                       should make use of.  maxcpus=n : n >= 0 limits the
-                       kernel to using 'n' processors.  n=0 is a special case,
-                       it is equivalent to "nosmp", which also disables
-                       the IO APIC.
+                       will bring up during bootup.  maxcpus=n : n >= 0 limits
+                       the kernel to bring up 'n' processors. Surely after
+                       bootup you can bring up the other plugged cpu by executing
+                       "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus
+                       only takes effect during system bootup.
+                       While n=0 is a special case, it is equivalent to "nosmp",
+                       which also disables the IO APIC.
 
        max_loop=       [LOOP] The number of loop block devices that get
        (loop.max_loop) unconditionally pre-created at init time. The default
@@ -2576,8 +2588,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
        nodelayacct     [KNL] Disable per-task delay accounting
 
-       nodisconnect    [HW,SCSI,M68K] Disables SCSI disconnects.
-
        nodsp           [SH] Disable hardware DSP at boot time.
 
        noefi           Disable EFI runtime services support.
@@ -2778,9 +2788,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
        nr_cpus=        [SMP] Maximum number of processors that an SMP kernel
                        could support.  nr_cpus=n : n >= 1 limits the kernel to
-                       supporting 'n' processors. Later in runtime you can not
-                       use hotplug cpu feature to put more cpu back to online.
-                       just like you compile the kernel NR_CPUS=n
+                       support 'n' processors. It could be larger than the
+                       number of already plugged CPU during bootup, later in
+                       runtime you can physically add extra cpu until it reaches
+                       n. So during boot up some boot time memory for per-cpu
+                       variables need be pre-allocated for later physical cpu
+                       hot plugging.
 
        nr_uarts=       [SERIAL] maximum number of UARTs to be registered.
 
@@ -3254,6 +3267,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
        raid=           [HW,RAID]
                        See Documentation/md.txt.
 
+       ram_latent_entropy
+                       Enable a very simple form of latent entropy extraction
+                       from the first 4GB of memory as the bootmem allocator
+                       passes the memory pages to the buddy allocator.
+
        ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
                        See Documentation/blockdev/ramdisk.txt.