Merge tag 'please-pull-ia64_for_5.4' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-microblaze.git] / Documentation / admin-guide / kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4ace5af..0d2a67e 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1732,6 +1732,11 @@
                        Note that using this option lowers the security
                        provided by tboot because it makes the system
                        vulnerable to DMA attacks.
+               nobounce [Default off]
+                       Disable bounce buffer for unstrusted devices such as
+                       the Thunderbolt devices. This will treat the untrusted
+                       devices as the trusted ones, hence might expose security
+                       risks of DMA attacks.
 
        intel_idle.max_cstate=  [KNL,HW,ACPI,X86]
                        0       disables intel_idle and fall back on acpi_idle.
@@ -1811,7 +1816,7 @@
                          synchronously.
 
        iommu.passthrough=
-                       [ARM64] Configure DMA to bypass the IOMMU by default.
+                       [ARM64, X86] Configure DMA to bypass the IOMMU by default.
                        Format: { "0" | "1" }
                        0 - Use IOMMU translation for DMA.
                        1 - Bypass the IOMMU for DMA.
@@ -2604,7 +2609,7 @@
                                expose users to several CPU vulnerabilities.
                                Equivalent to: nopti [X86,PPC]
                                               kpti=0 [ARM64]
-                                              nospectre_v1 [PPC]
+                                              nospectre_v1 [X86,PPC]
                                               nobp=0 [S390]
                                               nospectre_v2 [X86,PPC,S390,ARM64]
                                               spectre_v2_user=off [X86]
@@ -2965,9 +2970,9 @@
                        nosmt=force: Force disable SMT, cannot be undone
                                     via the sysfs control file.
 
-       nospectre_v1    [PPC] Disable mitigations for Spectre Variant 1 (bounds
-                       check bypass). With this option data leaks are possible
-                       in the system.
+       nospectre_v1    [X86,PPC] Disable mitigations for Spectre Variant 1
+                       (bounds check bypass). With this option data leaks are
+                       possible in the system.
 
        nospectre_v2    [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for
                        the Spectre variant 2 (indirect branch prediction)
@@ -4090,6 +4095,13 @@
                        Run specified binary instead of /init from the ramdisk,
                        used for early userspace startup. See initrd.
 
+       rdrand=         [X86]
+                       force - Override the decision by the kernel to hide the
+                               advertisement of RDRAND support (this affects
+                               certain AMD processors because of buggy BIOS
+                               support, specifically around the suspend/resume
+                               path).
+
        rdt=            [HW,X86,RDT]
                        Turn on/off individual RDT features. List is:
                        cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,