[Xen-changelog] [xen staging] x86/microcode: improve documentation for ucode=

[patchbot@xxxxxxx]

commit 6e73e7186dd73e8f638730135c298474f49de6a4
Author:     Eslam Elnikety <elnikety@xxxxxxxxxx>
AuthorDate: Fri Jan 24 10:30:54 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jan 24 10:30:54 2020 +0100

    x86/microcode: improve documentation for ucode=
    
    Specify applicability and the default value. Also state that, in case of
    EFI, the microcode update blob specified in the EFI cfg takes precedence
    over `ucode=scan`, if the latter is specified on Xen commend line.
    
    No functional changes.
    
    Signed-off-by: Eslam Elnikety <elnikety@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 docs/misc/xen-command-line.pandoc | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/docs/misc/xen-command-line.pandoc 
b/docs/misc/xen-command-line.pandoc
index e0e16fbef1..5eb3a07276 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -2137,10 +2137,15 @@ logic applies:
    opted in to with `smt=0 spec-ctrl=md-clear`, at which point TSX will remain
    active by default.
 
-### ucode (x86)
+### ucode
 > `= List of [ <integer> | scan=<bool>, nmi=<bool> ]`
 
-Specify how and where to find CPU microcode update blob.
+    Applicability: x86
+    Default: `nmi`
+
+Controls for CPU microcode loading. For early loading, this parameter can
+specify how and where to find the microcode update blob. For late loading,
+this parameter specifies if the update happens within a NMI handler.
 
 'integer' specifies the CPU microcode update blob module index. When positive,
 this specifies the n-th module (in the GrUB entry, zero based) to be used
@@ -2158,6 +2163,8 @@ image that contains microcode. Depending on the platform 
the blob with the
 microcode in the cpio name space must be:
   - on Intel: kernel/x86/microcode/GenuineIntel.bin
   - on AMD  : kernel/x86/microcode/AuthenticAMD.bin
+When using xen.efi, the `ucode=<filename>` config file setting takes
+precedence over `scan`.
 
 'nmi' determines late loading is performed in NMI handler or just in
 stop_machine context. In NMI handler, even NMIs are blocked, which is
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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