Merge branches 'acpi-bus', 'acpi-button', 'acpi-sysfs' and 'acpi-misc'

[thirdparty/linux.git] / Documentation / admin-guide / kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 02724bd017cc8fee31b933bc489a540f984a51c4..9c23934c28a9e601accb23598f8e4233b4f5ab9c 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1168,7 +1168,8 @@
                        Format: {"off" | "on" | "skip[mbr]"}
 
        efi=            [EFI]
-                       Format: { "old_map", "nochunk", "noruntime", "debug" }
+                       Format: { "old_map", "nochunk", "noruntime", "debug",
+                                 "nosoftreserve" }
                        old_map [X86-64]: switch to the old ioremap-based EFI
                        runtime services mapping. 32-bit still uses this one by
                        default.
@@ -1177,6 +1178,12 @@
                        firmware implementations.
                        noruntime : disable EFI runtime services support
                        debug: enable misc debug output
+                       nosoftreserve: The EFI_MEMORY_SP (Specific Purpose)
+                       attribute may cause the kernel to reserve the
+                       memory range for a memory mapping driver to
+                       claim. Specify efi=nosoftreserve to disable this
+                       reservation and treat the memory by its base type
+                       (i.e. EFI_CONVENTIONAL_MEMORY / "System RAM").
 
        efi_no_storage_paranoia [EFI; X86]
                        Using this parameter you can use more than 50% of
@@ -1189,15 +1196,21 @@
                        updating original EFI memory map.
                        Region of memory which aa attribute is added to is
                        from ss to ss+nn.
+
                        If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
                        is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
                        attribute is added to range 0x100000000-0x180000000 and
                        0x10a0000000-0x1120000000.
 
+                       If efi_fake_mem=8G@9G:0x40000 is specified, the
+                       EFI_MEMORY_SP(0x40000) attribute is added to
+                       range 0x240000000-0x43fffffff.
+
                        Using this parameter you can do debugging of EFI memmap
-                       related feature. For example, you can do debugging of
+                       related features. For example, you can do debugging of
                        Address Range Mirroring feature even if your box
-                       doesn't support it.
+                       doesn't support it, or mark specific memory as
+                       "soft reserved".
 
        efivar_ssdt=    [EFI; X86] Name of an EFI variable that contains an SSDT
                        that is to be dynamically loaded by Linux. If there are
@@ -2473,6 +2486,12 @@
                                     SMT on vulnerable CPUs
                        off        - Unconditionally disable MDS mitigation
 
+                       On TAA-affected machines, mds=off can be prevented by
+                       an active TAA mitigation as both vulnerabilities are
+                       mitigated with the same mechanism so in order to disable
+                       this mitigation, you need to specify tsx_async_abort=off
+                       too.
+
                        Not specifying this option is equivalent to
                        mds=full.
 
@@ -3110,9 +3129,9 @@
                        [X86,PV_OPS] Disable paravirtualized VMware scheduler
                        clock and use the default one.
 
-       no-steal-acc    [X86,KVM] Disable paravirtualized steal time accounting.
-                       steal time is computed, but won't influence scheduler
-                       behaviour
+       no-steal-acc    [X86,KVM,ARM64] Disable paravirtualized steal time
+                       accounting. steal time is computed, but won't
+                       influence scheduler behaviour
 
        nolapic         [X86-32,APIC] Do not enable or use the local APIC.
 
@@ -4931,6 +4950,11 @@
                                     vulnerable to cross-thread TAA attacks.
                        off        - Unconditionally disable TAA mitigation
 
+                       On MDS-affected machines, tsx_async_abort=off can be
+                       prevented by an active MDS mitigation as both vulnerabilities
+                       are mitigated with the same mechanism so in order to disable
+                       this mitigation, you need to specify mds=off too.
+
                        Not specifying this option is equivalent to
                        tsx_async_abort=full.  On CPUs which are MDS affected
                        and deploy MDS mitigation, TAA mitigation is not