At Wed, 31 Mar 2021 21:58:48 -0400, Thor Lancelot Simon <tls%panix.com@localhost> wrote: Subject: Re: nothing contributing entropy in Xen domUs? (causing python3.7 rebuild to get stuck in kernel in "entropy" during an "import" statement) > > On Wed, Mar 31, 2021 at 11:24:07AM +0200, Manuel Bouyer wrote: > > On Tue, Mar 30, 2021 at 10:42:53PM +0000, Taylor R Campbell wrote: > > > > > > There are no virtual RNG devices on the system in question, according > > > to the quoted `rndctl -l' output. Perhaps the VM host needs to be > > > taught to expose a virtio-rng device to the guest? > > > > There is no such thing in Xen. > > Is the CPU so old that it doesn't have RDRAND / RDSEED, or is Xen perhaps > masking these CPU features from the guest? So I don't quite know how to tell for sure (because "cpuid", for one, doesn't seem to even seem to include strings within it to report either of those features, and because figuring it out from the magic names given in places like Wikipedia is too hard), but in theory my CPU is very much new enough to have at least one of those features. In this particular example server it's in a Dell R510 with a pair of 6-core E5645 CPUs that "cpuid" shows the following for (in the dom0): # cpuid eax in eax ebx ecx edx 00000000 0000000b 756e6547 6c65746e 49656e69 00000001 000206c2 20200800 029ee3ff bfebfbff 00000002 55035a01 00f0b2ff 00000000 00ca0000 00000003 00000000 00000000 00000000 00000000 00000004 3c004121 01c0003f 0000003f 00000000 00000005 00000040 00000040 00000003 00001120 00000006 00000007 00000002 00000001 00000000 00000007 00000000 00000000 00000000 00000000 00000008 00000000 00000000 00000000 00000000 00000009 00000000 00000000 00000000 00000000 0000000a 07300403 00000004 00000000 00000603 0000000b 00000001 00000002 00000100 00000020 80000000 80000008 00000000 00000000 00000000 80000001 00000000 00000000 00000001 2c100800 80000002 65746e49 2952286c 6f655820 2952286e 80000003 55504320 20202020 20202020 45202020 80000004 35343635 20402020 30342e32 007a4847 80000005 00000000 00000000 00000000 00000000 80000006 00000000 00000000 01006040 00000000 80000007 00000000 00000000 00000000 00000100 80000008 00003028 00000000 00000000 00000000 Vendor ID: "GenuineIntel"; CPUID level 11 Intel-specific functions: Version 000206c2: Type 0 - Original OEM Family 6 - Pentium Pro Model 12 - Stepping 2 Reserved 8 Extended brand string: "Intel(R) Xeon(R) CPU E5645 @ 2.40GHz" CLFLUSH instruction cache line size: 8 Initial APIC ID: 32 Hyper threading siblings: 32 Feature flags bfebfbff: FPU Floating Point Unit VME Virtual 8086 Mode Enhancements DE Debugging Extensions PSE Page Size Extensions TSC Time Stamp Counter MSR Model Specific Registers PAE Physical Address Extension MCE Machine Check Exception CX8 COMPXCHG8B Instruction APIC On-chip Advanced Programmable Interrupt Controller present and enabled SEP Fast System Call MTRR Memory Type Range Registers PGE PTE Global Flag MCA Machine Check Architecture CMOV Conditional Move and Compare Instructions FGPAT Page Attribute Table PSE-36 36-bit Page Size Extension CLFSH CFLUSH instruction DS Debug store ACPI Thermal Monitor and Clock Ctrl MMX MMX instruction set FXSR Fast FP/MMX Streaming SIMD Extensions save/restore SSE Streaming SIMD Extensions instruction set SSE2 SSE2 extensions SS Self Snoop HT Hyper Threading TM Thermal monitor 31 reserved TLB and cache info: 5a: unknown TLB/cache descriptor 03: Data TLB: 4KB pages, 4-way set assoc, 64 entries 55: unknown TLB/cache descriptor ff: unknown TLB/cache descriptor b2: unknown TLB/cache descriptor f0: unknown TLB/cache descriptor ca: unknown TLB/cache descriptor Processor serial: 0002-06C2-0000-0000-0000-0000 Xen does indeed hide features in the vcpu it presents to a PV domU: $ cpuid eax in eax ebx ecx edx 00000000 0000000b 756e6547 6c65746e 49656e69 00000001 000206c2 22200800 02982203 1fc9cbf5 00000002 55035a01 00f0b2ff 00000000 00ca0000 00000003 00000000 00000000 00000000 00000000 00000004 3c004121 01c0003f 0000003f 00000000 00000005 00000040 00000040 00000003 00001120 00000006 00000007 00000002 00000001 00000000 00000007 00000000 00000000 00000000 00000000 00000008 00000000 00000000 00000000 00000000 00000009 00000000 00000000 00000000 00000000 0000000a 07300403 00000004 00000000 00000603 0000000b 00000001 00000002 00000100 00000022 80000000 80000008 00000000 00000000 00000000 80000001 00000000 00000000 00000001 20100800 80000002 65746e49 2952286c 6f655820 2952286e 80000003 55504320 20202020 20202020 45202020 80000004 35343635 20402020 30342e32 007a4847 80000005 00000000 00000000 00000000 00000000 80000006 00000000 00000000 01006040 00000000 80000007 00000000 00000000 00000000 00000100 80000008 00003028 00000000 00000000 00000000 Vendor ID: "GenuineIntel"; CPUID level 11 Intel-specific functions: Version 000206c2: Type 0 - Original OEM Family 6 - Pentium Pro Model 12 - Stepping 2 Reserved 8 Extended brand string: "Intel(R) Xeon(R) CPU E5645 @ 2.40GHz" CLFLUSH instruction cache line size: 8 Initial APIC ID: 34 Hyper threading siblings: 32 Feature flags 1fc9cbf5: FPU Floating Point Unit DE Debugging Extensions TSC Time Stamp Counter MSR Model Specific Registers PAE Physical Address Extension MCE Machine Check Exception CX8 COMPXCHG8B Instruction APIC On-chip Advanced Programmable Interrupt Controller present and enabled SEP Fast System Call MCA Machine Check Architecture CMOV Conditional Move and Compare Instructions FGPAT Page Attribute Table CLFSH CFLUSH instruction ACPI Thermal Monitor and Clock Ctrl MMX MMX instruction set FXSR Fast FP/MMX Streaming SIMD Extensions save/restore SSE Streaming SIMD Extensions instruction set SSE2 SSE2 extensions SS Self Snoop HT Hyper Threading TLB and cache info: 5a: unknown TLB/cache descriptor 03: Data TLB: 4KB pages, 4-way set assoc, 64 entries 55: unknown TLB/cache descriptor ff: unknown TLB/cache descriptor b2: unknown TLB/cache descriptor f0: unknown TLB/cache descriptor ca: unknown TLB/cache descriptor Processor serial: 0002-06C2-0000-0000-0000-0000 I noted today though that entropy doesn't seem to be accumulating even in the dom0 despite there being many useful sources configured to both collect and "estimate" _and_ despite the fact there's a valid-looking $random_file that was saved and reloaded by /etc/rc.d/random_seed (and saved again every day by /etc/security): # /etc/rc.d/random_seed rcvar # random_seed random_seed=YES # ls -l /etc/entropy-file -rw------- 1 root wheel 536 Mar 31 04:15 /etc/entropy-file # rndctl -l Source Bits Type Flags ipmi0-Temp 0 env estimate, collect, v, t, dv, dt ipmi0-Temp1 0 env estimate, collect, v, t, dv, dt ipmi0-Temp2 0 env estimate, collect, v, t, dv, dt ipmi0-Temp3 0 env estimate, collect, v, t, dv, dt ipmi0-Ambient-T 0 env estimate, collect, v, t, dv, dt ipmi0-Planar-Te 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-1 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-1 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-2 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-2 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-3 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-3 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-4 0 env estimate, collect, v, t, dv, dt ipmi0-Status 0 ??? estimate, collect, t, dt ipmi0-Voltage 0 power estimate, collect, v, t, dv, dt ipmi0-Voltage1 0 power estimate, collect, v, t, dv, dt ipmi0-Status1 0 ??? estimate, collect, t, dt ipmi0-Intrusion 0 ??? estimate, collect, t, dt ipmi0-Temp4 0 env estimate, collect, v, t, dv, dt ipmi0-Temp5 0 env estimate, collect, v, t, dv, dt ipmi0-Temp6 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-4 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-5 0 env estimate, collect, v, t, dv, dt ipmi0-FAN-MOD-5 0 env estimate, collect, v, t, dv, dt ipmi0-Ambient-T 0 env estimate, collect, v, t, dv, dt ipmi0-Ambient-T 0 env estimate, collect, v, t, dv, dt ums0 0 tty estimate, collect, v, t, dt ukbd0 0 tty estimate, collect, v, t, dt /dev/random 0 ??? estimate, collect, v sd2 0 disk estimate, collect, v, t, dt sd1 0 disk estimate, collect, v, t, dt sd0 0 disk estimate, collect, v, t, dt cpu0 0 vm estimate, collect, v, t, dv hardclock 0 skew estimate, collect, t pckbd0 0 tty estimate, collect, v, t, dt system-power 0 power estimate, collect, v, t, dt autoconf 0 ??? estimate, collect, t seed 0 ??? estimate, collect, v # sysctl kern.entropy kern.entropy.collection = 1 kern.entropy.depletion = 0 kern.entropy.consolidate = -23552 kern.entropy.gather = -23552 kern.entropy.needed = 256 kern.entropy.pending = 0 kern.entropy.epoch = 19 -- Greg A. Woods <gwoods%acm.org@localhost> Kelowna, BC +1 250 762-7675 RoboHack <woods%robohack.ca@localhost> Planix, Inc. <woods%planix.com@localhost> Avoncote Farms <woods%avoncote.ca@localhost>
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