From: Theodore Ts'o <firstname.lastname@example.org> To: Alden Tondettar <email@example.com>, Arnd Bergmann <firstname.lastname@example.org>, Greg Kroah-Hartman <email@example.com>, firstname.lastname@example.org, email@example.com Subject: Re: [PATCH] random: Don't overwrite CRNG state in crng_initialize() Date: Thu, 9 Feb 2017 13:32:42 -0500 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> OK, I figured out what is going on with your test results. If you use qemu-system-x86_64 **without** --enable-kvm, then on both the Debian Jessie version of qemu as well as the Debian Stretch version of qemu, crng_fast_load() will be called _twice_ before crng_initialize has a chance to be called. At least for my kernel configuration and my CPU. If you're using a different kernel configuration and a slower CPU, such that when qemu is doing instruction by instruction emulation, which slows down the boot sequence **massively**, then that probably explains your results. I'm not sure if there are any real life use cases where someone would be insane enough to use virtualization without enabling KVM, but at least we know what is happening now. This makes me feel better, because I've looked at kernel boot messags from a variety of systems, from big data center servers to laptops to mobile handsets, and I had **never** seen the sequence of crng initialization messages that you had been reporting. - Ted
next prev parent reply other threads:[~2017-02-09 18:32 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-02-09 3:31 Alden Tondettar 2017-02-09 4:19 ` Theodore Ts'o 2017-02-09 8:13 ` Alden Tondettar 2017-02-09 17:56 ` Theodore Ts'o 2017-02-09 18:32 ` Theodore Ts'o [this message] 2017-02-09 6:47 ` Greg Kroah-Hartman 2017-02-09 9:04 ` Alden Tondettar 2017-02-09 9:23 ` Greg Kroah-Hartman 2017-02-09 9:26 ` Stephan Müller
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