根据英特尔微码更新于 2018 年 3 月 12 日发布，旨在解决 Spectre/Meltdown，微代码与 CentOS 6 不兼容。
因此，运行 CentOS 6 的系统仍然容易受到 Spectre 变体 2 的影响，因为 CentOS 维护者将此补丁的责任委托给上游供应商（又名英特尔）。
我们已经安装了所有可用的操作系统更新，并且已成功针对 CentOS 6 系统上的 Spectre Variant 1 和 Meltdown 进行修补。
Spectre and Meltdown mitigation detection tool v0.35
Checking for vulnerabilities on current system
Kernel is Linux 2.6.32-696.23.1.el6.x86_64 #1 SMP Tue Mar 13 22:44:18 UTC 2018 x86_64
CPU is Intel(R) Xeon(R) CPU E3-1220 V2 @ 3.10GHz
Hardware check
* Hardware support (CPU microcode) for mitigation techniques
* Indirect Branch Restricted Speculation (IBRS)
* SPEC_CTRL MSR is available: NO
* CPU indicates IBRS capability: NO
* Indirect Branch Prediction Barrier (IBPB)
* PRED_CMD MSR is available: NO
* CPU indicates IBPB capability: NO
* Single Thread Indirect Branch Predictors (STIBP)
* SPEC_CTRL MSR is available: NO
* CPU indicates STIBP capability: NO
* Enhanced IBRS (IBRS_ALL)
* CPU indicates ARCH_CAPABILITIES MSR availability: NO
* ARCH_CAPABILITIES MSR advertises IBRS_ALL capability: NO
* CPU explicitly indicates not being vulnerable to Meltdown (RDCL_NO): NO
* CPU microcode is known to cause stability problems: NO (model 58 stepping 9 ucode 31)
* CPU vulnerability to the three speculative execution attacks variants
* Vulnerable to Variant 1: YES
* Vulnerable to Variant 2: YES
* Vulnerable to Variant 3: YES
CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1'
* Mitigated according to the /sys interface: YES (kernel confirms that the mitigation is active)
* Kernel has array_index_mask_nospec: NO
* Kernel has the Red Hat/Ubuntu patch: YES
> STATUS: NOT VULNERABLE (Mitigation: Load fences)
CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2'
* Mitigated according to the /sys interface: NO (kernel confirms your system is vulnerable)
* Mitigation 1
* Kernel is compiled with IBRS/IBPB support: YES
* Currently enabled features
* IBRS enabled for Kernel space: NO
* IBRS enabled for User space: NO
* IBPB enabled: YES
* Mitigation 2
* Kernel compiled with retpoline option: YES
* Kernel compiled with a retpoline-aware compiler: UNKNOWN
> STATUS: VULNERABLE (Vulnerable: Retpoline with unsafe module(s))
CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3'
* Mitigated according to the /sys interface: YES (kernel confirms that the mitigation is active)
* Kernel supports Page Table Isolation (PTI): YES
* PTI enabled and active: YES
* Running as a Xen PV DomU: NO
> STATUS: NOT VULNERABLE (Mitigation: PTI)
A false sense of security is worse than no security at all, see --disclaimer
这在运行 CentOS 6.9 的多个系统上是相同的。
我们如何针对 Spectre 变体 2 修补运行 CentOS 6 的系统？
答案1
说真的，你可以完全忽略英特尔下载中心的操作系统兼容性列表，至少对于微代码分发来说是这样。它绝对一文不值。
微码更新包与采用英特尔微码更新的所有内容兼容。那东西的 ABI 已经有十五年没有发生过相关变化了。
CentOS 6.9 中的内核是否会利用微码更新引入的新功能是另一回事，即使不这样做，也不会使其与微码更新不兼容。
就此而言，他们关于如何将微代码上传到处理器的说明也是完全错误的（内核永远无法处理基于文本的格式）。
假设您无法从 CentOS 的其他分支获取 intel 微码更新的 SRPM 并进行重建，您可以只安装旧版本，并将 RPM 安装的微码数据文件替换为 intel tarball 中的等效文件。 不要忘记重建 initramfs/initrd 并重新启动以尽早应用更新。
或者您可以等待，CentOS 最终将发布更新，其他人也会如此。大多数（全部？）发行版已经在其不稳定或 beta 测试分支中提供了这些更新，并且它们最终将迁移到稳定版本（时间取决于发行版）。