Hello, I upgraded from Debian 11 to Debian 12, and my random number generator disappeared. When I boot vmlinuz-5.10.0-23-amd64, there are two hardware random number generators available: # cat /sys/class/misc/hw_random/rng_available ccp-1-rng tpm-rng-0 ccp-1-rng is nonfunctional because AMD's "Cryptographic Coprocessor" is too secretive to work with Coreboot, so I've been using tpm-rng-0. When I boot vmlinuz-6.1.0-11-amd64, there is no tpm-rng-0. Only the nonfunctional ccp-1-rng is available: # cat /sys/class/misc/hw_random/rng_available ccp-1-rng The hardware is an APU2 from PC Engines with this TPM board: https://www.pcengines.ch/tpm1a.htm The actual TPM seems to be SLB 9665TT2.0 from Infineon, (although the writing on the actual chip differs from Infineon's rendering): https://www.infineon.com/cms/en/product/security-smart-card-solutions/optiga-embedded-security-solutions/optiga-tpm/slb-9665tt2.0/ The TPM seems to still exist as /dev/tpm0, but its random number generator is somehow unavailable. Rebooting to Linux 5.10 makes tpm-rng-0 reappear and provide seemingly random numbers like it always did. That rules out a hardware problem. It's some difference between the two kernels, but so far I haven't found anything obvious in the Linux source code. Is there anything that can be done, or is support for this random number generator just gone from Linux 6.1? Björn Persson
Attachment:
pgpZ584yTC1ZI.pgp
Description: OpenPGP digital signatur