From: David Laight <David.Laight@ACULAB.COM>
To: 'Pavel Machek' <pavel@ucw.cz>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Ahmed S. Darwish" <darwish.07@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Nicholas Mc Guire <hofrat@opentech.at>,
the arch/x86 maintainers <x86@kernel.org>,
Andy Lutomirski <luto@kernel.org>,
Kees Cook <keescook@chromium.org>
Subject: RE: x86/random: Speculation to the rescue
Date: Wed, 9 Oct 2019 09:37:56 +0000 [thread overview]
Message-ID: <0ee565c2378a4abab6b623d6d3e10a7f@AcuMS.aculab.com> (raw)
In-Reply-To: <20191009080240.GA11561@amd>
From: Pavel Machek
> Sent: 09 October 2019 09:03
> > NAND flash requires ECC so is likely to be async.
> > But I2C is clocked from the cpu end - so is fixed.
>
> RTC i2c may be clocked from the CPU end, but the time source needs to
> work when machine is off, so that has a separate crystal for
> timekeeping.
That only helps if the rtc chip lets you read its internal counters.
You get one read of a few bits of 'randomness'.
> > Also an embedded system could be booting off a large serial EEPROM.
> > These have fixed timings and are clocked from the cpu end.
>
> Have you seen such system running Linux?
You can run Linux on the Nios cpu on an Altera/Intel FPGA.
The kernel is likely to be loaded from the same serial eeprom as the FPGA image.
I've not personally run such a setup, but there are examples for the dev boards
so I assume some people do.
I'm not sure I'd want to run Linux on a 100MHz cpu with a slow memory interface.
Better finding an fpga with an arm core in the corner!
(We do use the Nios cpu - but for standalone code that fits in small internal
memory blocks.)
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2019-10-09 9:38 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-28 22:24 x86/random: Speculation to the rescue Thomas Gleixner
2019-09-28 23:53 ` Linus Torvalds
2019-09-29 7:40 ` Thomas Gleixner
2019-09-29 8:05 ` Alexander E. Patrakov
2019-09-30 1:16 ` Linus Torvalds
2019-09-30 2:59 ` Linus Torvalds
2019-09-30 6:10 ` Borislav Petkov
2019-09-30 16:06 ` Linus Torvalds
2019-10-01 13:51 ` Borislav Petkov
2019-10-01 17:14 ` Linus Torvalds
2019-10-01 17:50 ` [PATCH] char/random: Add a newline at the end of the file Borislav Petkov
2019-09-30 18:05 ` x86/random: Speculation to the rescue Kees Cook
2019-09-30 3:37 ` Theodore Y. Ts'o
2019-09-30 13:16 ` Theodore Y. Ts'o
2019-09-30 16:15 ` Linus Torvalds
2019-09-30 16:32 ` Peter Zijlstra
2019-09-30 17:03 ` Linus Torvalds
2019-10-01 10:28 ` David Laight
2019-10-15 21:50 ` Thomas Gleixner
2019-10-01 16:15 ` Ahmed S. Darwish
2019-10-01 16:37 ` Kees Cook
2019-10-01 17:18 ` Ahmed S. Darwish
2019-10-01 17:25 ` Linus Torvalds
2019-10-06 12:07 ` Pavel Machek
2019-10-02 12:01 ` Theodore Y. Ts'o
2019-10-06 11:41 ` Pavel Machek
2019-10-06 17:26 ` Linus Torvalds
2019-10-06 17:35 ` Pavel Machek
2019-10-06 18:06 ` Linus Torvalds
2019-10-06 18:21 ` Pavel Machek
2019-10-06 18:26 ` Linus Torvalds
2019-10-07 11:47 ` Theodore Y. Ts'o
2019-10-07 22:18 ` Pavel Machek
2019-10-08 11:33 ` David Laight
2019-10-09 8:02 ` Pavel Machek
2019-10-09 9:37 ` David Laight [this message]
2019-10-01 2:14 hgntkwis
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=0ee565c2378a4abab6b623d6d3e10a7f@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=darwish.07@gmail.com \
--cc=hofrat@opentech.at \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=pavel@ucw.cz \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=tytso@mit.edu \
--cc=x86@kernel.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: link
Be 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 NNTP newsgroup(s).