On Thu, Feb 02, 2023 at 07:57:37AM -0500, James Bottomley wrote: > On Thu, 2023-02-02 at 11:28 +0100, Linux kernel regression tracking > (Thorsten Leemhuis) wrote: > [...] > > So it's a firmware problem, but apparently one that Linux only > > triggers since 6.1. > > > > Jason, could the hwrng changes have anything to do with this? > > > > A bisection really would be helpful, but I guess that is not easy as > > the problem apparently only shows up after some time... > > the problem description says the fTPM causes system stutter when it > writes to NVRAM. Since an fTPM is a proprietary implementation, we > don't know what it does. The ms TPM implementation definitely doesn't > trigger NV writes on rng requests, but it is plausible this fTPM does > ... particularly if they have a time based input to the DRNG. Even if > this speculation is true, there's not much we can do about it, since > it's a firmware bug and AMD should have delivered the BIOS update that > fixes it. > > The way to test this would be to set the config option > > CONFIG_HW_RANDOM_TPM=n > > and see if the stutter goes away. I suppose if someone could quantify > the bad bioses, we could warn, but that's about it. > > James > And e.g. I do not have a Ryzen CPU so pretty hard to answer such question. BR, Jarkko
