From: "Maciej W. Rozycki" <macro@orcam.me.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
Arnd Bergmann <arnd@kernel.org>,
linux-alpha@vger.kernel.org,
Richard Henderson <richard.henderson@linaro.org>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Marc Zyngier <maz@kernel.org>,
linux-kernel@vger.kernel.org, Michael Cree <mcree@orcon.net.nz>,
Frank Scheiner <frank.scheiner@web.de>
Subject: Re: [PATCH 00/14] alpha: cleanups for 6.10
Date: Wed, 3 Jul 2024 01:12:52 +0100 (BST) [thread overview]
Message-ID: <alpine.DEB.2.21.2407020219040.38148@angie.orcam.me.uk> (raw)
In-Reply-To: <CAHk-=wihNu+_bGwD8F107ds7Lv1Z6ODTwvYYvXeW3im1=4R65w@mail.gmail.com>
On Mon, 1 Jul 2024, Linus Torvalds wrote:
> The architecture was wrong 30 years ago. It's not that it "became"
> wrong in hindsight. It was wrong originally, and it's just that people
> hadn't thought things through enough to realize how wrong it was.
>
> The only way it's not wrong is if you say "byte accesses do not
> matter". That's a very Cray way of looking at things - Cray 1 had a
> 64-bit "char" in C, because there were no byte accesses.
>
> That's fine if your only goal in life is to do HPC.
>
> So if you simply don't care about bytes, and you *only* work with
> words and quad-words, then alpha looks ok.
>
> But honestly, that's basically saying "in a different universe, alpha
> is not a mis-design".
Precisely my point! We got so used to think in multiples of 8 bits that
other approaches seem ridiculous.
The PDP-10 operated on 36-bit quantities and strings were essentially
clusters of 6-bit characters packed into 6-packs (which is also allegedly
where the C language's original limitation of using at most six characters
for identifiers came from -- so that the PDP-10 could compare a pair with
a single machine instruction).
So there was already legacy of doing things this way at DEC back in ~1990
and I can envisage engineers there actually thought that to have a machine
that in C terms has 32-bit shorts and ints, 64-bit longs and pointers, and
strings as clusters of 8-bit characters packed into 4-packs or 8-packs was
not at all unreasonable. Or maybe just plain 32-bit characters. After
all you don't absolutely *have* to use data types of 8 or 16 bits exactly
in width for anything, do you? NB for strings nowadays we have Unicode
and we could just use UTF-32 if not to waste memory.
And even now ISO C is very flexible on data type widths and only requires
the character data type to be at least 8 bits wide, and 16-bit and 24-bit
examples are actually given in the standard itself. Yes, POSIX requires
the character data type to be 8 bits wide exactly now, but POSIX.1-1988
deferred to ANSI C AFAICT.
Maciej
next prev parent reply other threads:[~2024-07-03 0:13 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-03 8:11 [PATCH 00/14] alpha: cleanups for 6.10 Arnd Bergmann
2024-05-03 8:11 ` [PATCH 01/14] alpha: sort scr_mem{cpy,move}w() out Arnd Bergmann
2024-05-03 8:11 ` [PATCH 02/14] alpha: fix modversions for strcpy() et.al Arnd Bergmann
2024-05-03 8:11 ` [PATCH 03/14] alpha: add clone3() support Arnd Bergmann
2024-05-03 8:11 ` [PATCH 04/14] alpha: don't make functions public without a reason Arnd Bergmann
2024-05-03 8:11 ` [PATCH 05/14] alpha: sys_sio: fix misspelled ifdefs Arnd Bergmann
2024-05-03 8:11 ` [PATCH 06/14] alpha: missing includes Arnd Bergmann
2024-05-03 8:11 ` [PATCH 07/14] alpha: core_lca: take the unused functions out Arnd Bergmann
2024-05-03 8:11 ` [PATCH 08/14] alpha: jensen, t2 - make __EXTERN_INLINE same as for the rest Arnd Bergmann
2024-05-03 8:11 ` [PATCH 09/14] alpha: trim the unused stuff from asm-offsets.c Arnd Bergmann
2024-05-03 8:11 ` [PATCH 10/14] alpha: remove DECpc AXP150 (Jensen) support Arnd Bergmann
2024-05-03 16:07 ` Linus Torvalds
2024-05-03 17:00 ` Al Viro
2024-05-03 20:07 ` Arnd Bergmann
2024-05-03 8:11 ` [PATCH 11/14] alpha: sable: remove early machine support Arnd Bergmann
2024-05-03 8:11 ` [PATCH 12/14] alpha: remove LCA and APECS based machines Arnd Bergmann
2024-05-03 8:11 ` [PATCH 13/14] alpha: cabriolet: remove EV5 CPU support Arnd Bergmann
2024-05-03 8:11 ` [PATCH 14/14] alpha: drop pre-EV56 support Arnd Bergmann
2024-05-04 15:00 ` Richard Henderson
2024-05-06 10:06 ` Arnd Bergmann
2024-06-03 6:02 ` Jiri Slaby
2024-06-04 13:58 ` Greg KH
2024-05-03 16:06 ` [PATCH 00/14] alpha: cleanups for 6.10 Matt Turner
2024-05-03 20:15 ` Arnd Bergmann
2024-05-06 9:16 ` Michael Cree
2024-05-06 10:11 ` Arnd Bergmann
2024-05-03 16:53 ` John Paul Adrian Glaubitz
2024-05-03 17:19 ` Paul E. McKenney
2024-05-27 23:49 ` Maciej W. Rozycki
2024-05-28 14:43 ` Paul E. McKenney
2024-05-29 18:50 ` Maciej W. Rozycki
2024-05-29 22:09 ` Paul E. McKenney
2024-05-30 22:59 ` Maciej W. Rozycki
2024-05-31 3:56 ` Maciej W. Rozycki
2024-05-31 19:33 ` Paul E. McKenney
2024-06-03 16:22 ` Maciej W. Rozycki
2024-06-03 17:08 ` Paul E. McKenney
2024-07-01 23:50 ` Maciej W. Rozycki
2024-05-30 1:08 ` Linus Torvalds
2024-05-30 22:57 ` Maciej W. Rozycki
2024-05-31 0:10 ` Linus Torvalds
2024-06-03 11:09 ` Maciej W. Rozycki
2024-06-03 11:36 ` John Paul Adrian Glaubitz
2024-06-03 16:57 ` Linus Torvalds
2024-07-01 23:48 ` Maciej W. Rozycki
2024-05-31 15:48 ` Arnd Bergmann
2024-05-31 16:32 ` Linus Torvalds
2024-05-31 16:54 ` Arnd Bergmann
2024-06-01 13:51 ` David Laight
2024-07-01 23:48 ` Maciej W. Rozycki
2024-07-02 1:13 ` Linus Torvalds
2024-07-03 0:12 ` Maciej W. Rozycki [this message]
2024-07-03 0:50 ` Linus Torvalds
2024-07-04 22:21 ` Maciej W. Rozycki
2024-06-03 11:33 ` Maciej W. Rozycki
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