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On 7/14/19 8:26 AM, Mick wrote: |
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> Then I came across this old message regarding Piledriver CPUs: |
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> https://lists.debian.org/debian-security/2016/03/msg00084.html The |
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> post refers to model 2 of cpu family 21. Not all models in the same |
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> family, only model 2. So I am thinking although patch files are named |
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> per CPU family, whether they are applicable and applied as an update |
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> to the CPU is probably determined by the particular CPU *model*. |
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> Logically, errata in previous CPU revisions may have been fixed in |
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> later models of the same family and therefore such microcode updates |
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> would not be needed. When offered by the OS the CPU won't select to |
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> have them applied. This explains why my AMD models, which are later |
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> revisions of the same 15h family do not apply any microcode updates - |
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> they don't need them. Please share if you know differently and thank |
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> you all for your responses. |
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Remember a while back when I mentioned that "lwp" had disappeared from |
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my /proc/cpuinfo? |
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They restored "lwp" with this commit : |
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> https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/commit/?id=7518922bd5b98b137af7aaf3c836f5a498e91609 |
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So it stands to reason that the microcode only applies specific patches |
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to specific problems per CPU. |
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|
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|
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Reference : |
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> Darkstar ~ # cat /proc/cpuinfo |
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> processor : 0 |
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> vendor_id : AuthenticAMD |
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> cpu family : 21 |
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> model : 2 |
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> model name : AMD FX(tm)-9590 Eight-Core Processor |
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> stepping : 0 |
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> microcode : 0x6000852 |
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> cpu MHz : 4685.390 |
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> cache size : 2048 KB |
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Output of /sys/devices/system/cpu/vulnerabilities : |
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> |
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> Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/l1tf |
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> Not affected |
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> Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/mds |
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> Not affected |
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> Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/meltdown |
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> Not affected |
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> Darkstar ~ # cat |
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> /sys/devices/system/cpu/vulnerabilities/spec_store_bypass |
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> Mitigation: Speculative Store Bypass disabled |
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> Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/spectre_v1 |
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> Mitigation: __user pointer sanitization |
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> Darkstar ~ # cat /sys/devices/system/cpu/vulnerabilities/spectre_v2 |
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> Mitigation: Full AMD retpoline, IBPB: always-on, STIBP: disabled, RSB |
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> filling |
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|
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Corbin |
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