public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "ecree429 at virginmedia dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/100444] std::random_device isn't random on AMD Date: Thu, 06 May 2021 08:48:33 +0000 [thread overview] Message-ID: <bug-100444-4-yL6bB4o4af@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-100444-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100444 --- Comment #2 from Edward Cree <ecree429 at virginmedia dot com> --- (In reply to Richard Biener from comment #1) > Isn't this worked around at kernel level by disabling RDRAND support on > affected CPUs? Not sure. I wondered if it might be, so I straced the process and it didn't seem to be making a system call, i.e. it's using the RDRAND instruction directly. >From the kernel docs on nordrand: > [X86] Disable kernel use of the RDRAND and > RDSEED instructions even if they are supported > by the processor. RDRAND and RDSEED are still > available to user space applications. But I suppose it might affect the vdso, or something else the lib uses to detect whether RDRAND is present. I've added nordrand to my kernel cmdline, so next time I reboot I'll be able to test this; idk when that'll be, though.
next prev parent reply other threads:[~2021-05-06 8:48 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-06 7:45 [Bug libstdc++/100444] New: " ecree429 at virginmedia dot com 2021-05-06 7:52 ` [Bug libstdc++/100444] " rguenth at gcc dot gnu.org 2021-05-06 8:48 ` ecree429 at virginmedia dot com [this message] 2021-05-06 8:49 ` pinskia at gcc dot gnu.org 2021-05-06 8:58 ` rguenth at gcc dot gnu.org 2021-05-06 10:05 ` redi at gcc dot gnu.org 2021-05-06 10:22 ` redi at gcc dot gnu.org 2021-05-06 10:51 ` ecree429 at virginmedia dot com 2021-05-06 11:25 ` redi at gcc dot gnu.org 2021-05-06 11:39 ` rguenth at gcc dot gnu.org 2021-05-06 11:41 ` redi at gcc dot gnu.org 2021-05-10 20:20 ` redi at gcc dot gnu.org 2021-05-13 18:46 ` ecree429 at virginmedia dot com 2021-05-14 9:23 ` redi at gcc dot gnu.org 2021-09-25 20:07 ` redi at gcc dot gnu.org 2021-10-04 12:20 ` redi at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-100444-4-yL6bB4o4af@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).