From: Arnd Bergmann <arnd@arndb.de>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
linux-arch <linux-arch@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Wedson Almeida Filho <wedsonaf@google.com>,
Gary Guo <gary@garyguo.net>, Hector Martin <marcan@marcan.st>,
Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [Question] Alignment requirement for readX() and writeX()
Date: Fri, 30 Jul 2021 22:24:53 +0200 [thread overview]
Message-ID: <CAK8P3a3_pgtUWrg-MpaVyVqhffeuvQECHCmSCLyudfSwuEcP_g@mail.gmail.com> (raw)
In-Reply-To: <YQQ3KAXrPN1CuglL@boqun-archlinux>
On Fri, Jul 30, 2021 at 7:31 PM Boqun Feng <boqun.feng@gmail.com> wrote:
> On Fri, Jul 30, 2021 at 06:58:30PM +0200, Arnd Bergmann wrote:
>
> If we want to check, I'd expect we do the checks inside
> readX()/writeX(), for example, readl() could be implemented as:
>
> #define readl(c) \
> ({ \
> u32 __v; \
> \
> /* alignment checking */ \
> BUG_ON(c & (sizeof(__v) - 1)); \
> __v = readl_relaxed(c); \
> __iormb(__v); \
> __v; \
> })
>
> It's a runtime check, so if anyone hates it I can understand ;-)
Right, I really don't think that adds any value, this just replaces one
oops message with a more different oops message, while adding
some overhead.
Arnd
next prev parent reply other threads:[~2021-07-30 20:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 16:42 [Question] Alignment requirement for readX() and writeX() Boqun Feng
2021-07-30 16:58 ` Arnd Bergmann
2021-07-30 17:30 ` Boqun Feng
2021-07-30 20:24 ` Arnd Bergmann [this message]
2021-07-31 1:51 ` Boqun Feng
2021-08-02 8:37 ` David Laight
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