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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	David Miller <davem@davemloft.net>,
	Greg KH <gregkh@linuxfoundation.org>,
	"Jason A . Donenfeld" <Jason@zx2c4.com>,
	Samuel Neves <sneves@dei.uc.pt>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Arnd Bergmann <arnd@arndb.de>, Eric Biggers <ebiggers@google.com>,
	Andy Lutomirski <luto@kernel.org>, Will Deacon <will@kernel.org>,
	Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [RFC PATCH 11/18] int128: move __uint128_t compiler test to Kconfig
Date: Wed, 25 Sep 2019 14:01:33 -0700	[thread overview]
Message-ID: <CAHk-=wi8+MHz8xGtx_mUZPBsRT6qkptGW7a_pOrK=SnTRAiecA@mail.gmail.com> (raw)
In-Reply-To: <20190925161255.1871-12-ard.biesheuvel@linaro.org>

On Wed, Sep 25, 2019 at 9:14 AM Ard Biesheuvel
<ard.biesheuvel@linaro.org> wrote:
>
>  config ARCH_SUPPORTS_INT128
>         bool
> +       depends on !$(cc-option,-D__SIZEOF_INT128__=0)

Hmm. Does this actually work?

If that "depends on" now ends up being 'n', afaik the people who
_enable_ it just do a

       select ARCH_SUPPORTS_INT128

and now you'll end up with the Kconfig erroring out with

   WARNING: unmet direct dependencies detected for ARCH_SUPPORTS_INT128

and then you end up with CONFIG_ARCH_SUPPORTS_INT128 anyway, instead
of the behavior you _want_ to get, which is to not get that CONFIG
defined at all.

So I heartily agree with your intent, but I don't think that model
works. I think you need to change the cases that currently do

       select ARCH_SUPPORTS_INT128

to instead have that cc-option test.

And take all the above with a pinch of salt. Maybe what you are doing
works, and I am just missing some piece of the puzzle. But I _think_
it's broken, and you didn't test with a compiler that doesn't support
that thing properly.

             Linus

  reply	other threads:[~2019-09-25 21:01 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 16:12 [RFC PATCH 00/18] crypto: wireguard using the existing crypto API Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 01/18] crypto: shash - add plumbing for operating on scatterlists Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 02/18] crypto: x86/poly1305 - implement .update_from_sg method Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 03/18] crypto: arm/poly1305 - incorporate OpenSSL/CRYPTOGAMS NEON implementation Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 04/18] crypto: arm64/poly1305 " Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 05/18] crypto: chacha - move existing library code into lib/crypto Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 06/18] crypto: rfc7539 - switch to shash for Poly1305 Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 07/18] crypto: rfc7539 - use zero reqsize for sync instantiations without alignmask Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 08/18] crypto: testmgr - add a chacha20poly1305 test case Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 09/18] crypto: poly1305 - move core algorithm into lib/crypto Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 10/18] crypto: poly1305 - add init/update/final library routines Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 11/18] int128: move __uint128_t compiler test to Kconfig Ard Biesheuvel
2019-09-25 21:01   ` Linus Torvalds [this message]
2019-09-25 21:19     ` Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 12/18] crypto: BLAKE2s - generic C library implementation and selftest Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 13/18] crypto: Curve25519 - generic C library implementations " Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 14/18] crypto: chacha20poly1305 - import construction and selftest from Zinc Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 15/18] net: WireGuard secure network tunnel Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 16/18] netlink: use new strict length types in policy for 5.2 Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 17/18] wg switch to lib/crypto algos Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 18/18] net: wireguard - switch to crypto API for packet encryption Ard Biesheuvel
2019-09-25 22:15   ` Linus Torvalds
2019-09-25 22:22     ` Linus Torvalds
2019-09-26  9:40     ` Pascal Van Leeuwen
2019-09-26 16:35       ` Linus Torvalds
2019-09-27  0:15         ` Pascal Van Leeuwen
2019-09-27  1:30           ` Linus Torvalds
2019-09-27  2:54             ` Linus Torvalds
2019-09-27  3:53               ` Herbert Xu
2019-09-27  4:37                 ` Andy Lutomirski
2019-09-27  4:59                   ` Herbert Xu
2019-09-27  4:01               ` Herbert Xu
2019-09-27  4:13                 ` Linus Torvalds
2019-09-27 10:44               ` Pascal Van Leeuwen
2019-09-27 11:08                 ` Pascal Van Leeuwen
2019-09-27  4:36             ` Andy Lutomirski
2019-09-27  9:58             ` Pascal Van Leeuwen
2019-09-27 10:11               ` Herbert Xu
2019-09-27 16:23               ` Linus Torvalds
2019-09-30 11:14                 ` France didn't want GSM encryption Marc Gonzalez
2019-09-30 21:37                   ` Linus Torvalds
2019-09-30 20:44                 ` [RFC PATCH 18/18] net: wireguard - switch to crypto API for packet encryption Pascal Van Leeuwen
2019-09-27  2:06           ` Linus Torvalds
2019-09-27 10:11             ` Pascal Van Leeuwen
2019-09-26 11:06     ` Ard Biesheuvel
2019-09-26 12:34       ` Ard Biesheuvel
2019-09-26  8:59 ` [RFC PATCH 00/18] crypto: wireguard using the existing crypto API Jason A. Donenfeld
2019-09-26 10:19   ` Pascal Van Leeuwen
2019-09-26 10:59     ` Jason A. Donenfeld
2019-09-26 11:06     ` chapoly acceleration hardware [Was: Re: [RFC PATCH 00/18] crypto: wireguard using the existing crypto API] Jason A. Donenfeld
2019-09-26 11:38       ` Toke Høiland-Jørgensen
2019-09-26 13:52       ` Pascal Van Leeuwen
2019-09-26 23:13         ` Dave Taht
2019-09-27 12:18           ` Pascal Van Leeuwen
2019-09-26 22:47       ` Jakub Kicinski
2019-09-26 12:07   ` [RFC PATCH 00/18] crypto: wireguard using the existing crypto API Ard Biesheuvel
2019-09-26 13:06     ` Pascal Van Leeuwen
2019-09-26 13:15       ` Ard Biesheuvel
2019-09-26 14:03         ` Pascal Van Leeuwen
2019-09-26 14:52           ` Ard Biesheuvel
2019-09-26 15:04             ` Pascal Van Leeuwen
2019-09-26 20:47     ` Jason A. Donenfeld
2019-09-26 21:22       ` Andrew Lunn
2019-09-26 21:36       ` Andy Lutomirski
2019-09-27  7:20         ` Jason A. Donenfeld
2019-10-01  8:56           ` Ard Biesheuvel

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