From 6e73e7186dd73e8f638730135c298474f49de6a4 Mon Sep 17 00:00:00 2001 From: Eslam Elnikety Date: Fri, 24 Jan 2020 10:30:54 +0100 Subject: [PATCH] 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 Reviewed-by: Jan Beulich --- 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 [ | scan=, nmi= ]` -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=` 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 -- 2.39.5