.. | .. |
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894 | 894 | |
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895 | 895 | debugpat [X86] Enable PAT debugging |
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896 | 896 | |
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897 | | - decnet.addr= [HW,NET] |
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898 | | - Format: <area>[,<node>] |
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899 | | - See also Documentation/networking/decnet.rst. |
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900 | | - |
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901 | 897 | default_hugepagesz= |
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902 | 898 | [HW] The size of the default HugeTLB page. This is |
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903 | 899 | the size represented by the legacy /proc/ hugepages |
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.. | .. |
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1487 | 1483 | gart_fix_e820= [X86-64] disable the fix e820 for K8 GART |
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1488 | 1484 | Format: off | on |
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1489 | 1485 | default: on |
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| 1486 | + |
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| 1487 | + gather_data_sampling= |
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| 1488 | + [X86,INTEL] Control the Gather Data Sampling (GDS) |
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| 1489 | + mitigation. |
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| 1490 | + |
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| 1491 | + Gather Data Sampling is a hardware vulnerability which |
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| 1492 | + allows unprivileged speculative access to data which was |
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| 1493 | + previously stored in vector registers. |
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| 1494 | + |
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| 1495 | + This issue is mitigated by default in updated microcode. |
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| 1496 | + The mitigation may have a performance impact but can be |
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| 1497 | + disabled. On systems without the microcode mitigation |
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| 1498 | + disabling AVX serves as a mitigation. |
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| 1499 | + |
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| 1500 | + force: Disable AVX to mitigate systems without |
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| 1501 | + microcode mitigation. No effect if the microcode |
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| 1502 | + mitigation is present. Known to cause crashes in |
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| 1503 | + userspace with buggy AVX enumeration. |
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| 1504 | + |
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| 1505 | + off: Disable GDS mitigation. |
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1490 | 1506 | |
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1491 | 1507 | gcov_persist= [GCOV] When non-zero (default), profiling data for |
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1492 | 1508 | kernel modules is saved and remains accessible via |
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.. | .. |
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2144 | 2160 | |
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2145 | 2161 | ivrs_ioapic [HW,X86-64] |
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2146 | 2162 | Provide an override to the IOAPIC-ID<->DEVICE-ID |
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2147 | | - mapping provided in the IVRS ACPI table. For |
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2148 | | - example, to map IOAPIC-ID decimal 10 to |
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2149 | | - PCI device 00:14.0 write the parameter as: |
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| 2163 | + mapping provided in the IVRS ACPI table. |
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| 2164 | + By default, PCI segment is 0, and can be omitted. |
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| 2165 | + |
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| 2166 | + For example, to map IOAPIC-ID decimal 10 to |
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| 2167 | + PCI segment 0x1 and PCI device 00:14.0, |
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| 2168 | + write the parameter as: |
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| 2169 | + ivrs_ioapic=10@0001:00:14.0 |
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| 2170 | + |
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| 2171 | + Deprecated formats: |
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| 2172 | + * To map IOAPIC-ID decimal 10 to PCI device 00:14.0 |
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| 2173 | + write the parameter as: |
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2150 | 2174 | ivrs_ioapic[10]=00:14.0 |
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| 2175 | + * To map IOAPIC-ID decimal 10 to PCI segment 0x1 and |
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| 2176 | + PCI device 00:14.0 write the parameter as: |
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| 2177 | + ivrs_ioapic[10]=0001:00:14.0 |
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2151 | 2178 | |
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2152 | 2179 | ivrs_hpet [HW,X86-64] |
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2153 | 2180 | Provide an override to the HPET-ID<->DEVICE-ID |
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2154 | | - mapping provided in the IVRS ACPI table. For |
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2155 | | - example, to map HPET-ID decimal 0 to |
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2156 | | - PCI device 00:14.0 write the parameter as: |
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| 2181 | + mapping provided in the IVRS ACPI table. |
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| 2182 | + By default, PCI segment is 0, and can be omitted. |
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| 2183 | + |
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| 2184 | + For example, to map HPET-ID decimal 10 to |
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| 2185 | + PCI segment 0x1 and PCI device 00:14.0, |
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| 2186 | + write the parameter as: |
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| 2187 | + ivrs_hpet=10@0001:00:14.0 |
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| 2188 | + |
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| 2189 | + Deprecated formats: |
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| 2190 | + * To map HPET-ID decimal 0 to PCI device 00:14.0 |
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| 2191 | + write the parameter as: |
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2157 | 2192 | ivrs_hpet[0]=00:14.0 |
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| 2193 | + * To map HPET-ID decimal 10 to PCI segment 0x1 and |
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| 2194 | + PCI device 00:14.0 write the parameter as: |
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| 2195 | + ivrs_ioapic[10]=0001:00:14.0 |
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2158 | 2196 | |
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2159 | 2197 | ivrs_acpihid [HW,X86-64] |
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2160 | 2198 | Provide an override to the ACPI-HID:UID<->DEVICE-ID |
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2161 | | - mapping provided in the IVRS ACPI table. For |
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2162 | | - example, to map UART-HID:UID AMD0020:0 to |
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2163 | | - PCI device 00:14.5 write the parameter as: |
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| 2199 | + mapping provided in the IVRS ACPI table. |
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| 2200 | + By default, PCI segment is 0, and can be omitted. |
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| 2201 | + |
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| 2202 | + For example, to map UART-HID:UID AMD0020:0 to |
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| 2203 | + PCI segment 0x1 and PCI device ID 00:14.5, |
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| 2204 | + write the parameter as: |
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| 2205 | + ivrs_acpihid=AMD0020:0@0001:00:14.5 |
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| 2206 | + |
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| 2207 | + Deprecated formats: |
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| 2208 | + * To map UART-HID:UID AMD0020:0 to PCI segment is 0, |
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| 2209 | + PCI device ID 00:14.5, write the parameter as: |
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2164 | 2210 | ivrs_acpihid[00:14.5]=AMD0020:0 |
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| 2211 | + * To map UART-HID:UID AMD0020:0 to PCI segment 0x1 and |
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| 2212 | + PCI device ID 00:14.5, write the parameter as: |
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| 2213 | + ivrs_acpihid[0001:00:14.5]=AMD0020:0 |
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2165 | 2214 | |
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2166 | 2215 | js= [HW,JOY] Analog joystick |
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2167 | 2216 | See Documentation/input/joydev/joystick.rst. |
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.. | .. |
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2310 | 2359 | |
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2311 | 2360 | kvm-arm.mode= |
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2312 | 2361 | [KVM,ARM] Select one of KVM/arm64's modes of operation. |
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| 2362 | + |
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| 2363 | + none: Forcefully disable KVM. |
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2313 | 2364 | |
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2314 | 2365 | nvhe: Standard nVHE-based mode, without support for |
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2315 | 2366 | protected guests. |
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.. | .. |
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2918 | 2969 | Disable all optional CPU mitigations. This |
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2919 | 2970 | improves system performance, but it may also |
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2920 | 2971 | expose users to several CPU vulnerabilities. |
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2921 | | - Equivalent to: nopti [X86,PPC] |
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| 2972 | + Equivalent to: gather_data_sampling=off [X86] |
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2922 | 2973 | kpti=0 [ARM64] |
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2923 | | - nospectre_v1 [X86,PPC] |
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2924 | | - nobp=0 [S390] |
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2925 | | - nospectre_v2 [X86,PPC,S390,ARM64] |
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2926 | | - spectre_v2_user=off [X86] |
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2927 | | - spec_store_bypass_disable=off [X86,PPC] |
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2928 | | - ssbd=force-off [ARM64] |
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| 2974 | + kvm.nx_huge_pages=off [X86] |
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2929 | 2975 | l1tf=off [X86] |
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2930 | 2976 | mds=off [X86] |
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2931 | | - tsx_async_abort=off [X86] |
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2932 | | - kvm.nx_huge_pages=off [X86] |
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| 2977 | + mmio_stale_data=off [X86] |
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2933 | 2978 | no_entry_flush [PPC] |
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2934 | 2979 | no_uaccess_flush [PPC] |
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2935 | | - mmio_stale_data=off [X86] |
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| 2980 | + nobp=0 [S390] |
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| 2981 | + nopti [X86,PPC] |
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| 2982 | + nospectre_v1 [X86,PPC] |
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| 2983 | + nospectre_v2 [X86,PPC,S390,ARM64] |
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2936 | 2984 | retbleed=off [X86] |
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| 2985 | + spec_store_bypass_disable=off [X86,PPC] |
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| 2986 | + spectre_v2_user=off [X86] |
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| 2987 | + ssbd=force-off [ARM64] |
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| 2988 | + tsx_async_abort=off [X86] |
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2937 | 2989 | |
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2938 | 2990 | Exceptions: |
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2939 | 2991 | This does not have any effect on |
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.. | .. |
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5191 | 5243 | Not specifying this option is equivalent to |
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5192 | 5244 | spectre_v2_user=auto. |
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5193 | 5245 | |
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| 5246 | + spec_rstack_overflow= |
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| 5247 | + [X86] Control RAS overflow mitigation on AMD Zen CPUs |
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| 5248 | + |
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| 5249 | + off - Disable mitigation |
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| 5250 | + microcode - Enable microcode mitigation only |
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| 5251 | + safe-ret - Enable sw-only safe RET mitigation (default) |
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| 5252 | + ibpb - Enable mitigation by issuing IBPB on |
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| 5253 | + kernel entry |
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| 5254 | + ibpb-vmexit - Issue IBPB only on VMEXIT |
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| 5255 | + (cloud-specific mitigation) |
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| 5256 | + |
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5194 | 5257 | spec_store_bypass_disable= |
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5195 | 5258 | [HW] Control Speculative Store Bypass (SSB) Disable mitigation |
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5196 | 5259 | (Speculative Store Bypass vulnerability) |
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