From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
clang-built-linux@googlegroups.com
Subject: Re: [PATCH] ARM: mtd-xip: work around clang/llvm bug
Date: Tue, 9 Jul 2019 13:25:50 +0100 [thread overview]
Message-ID: <20190709122550.nau44z32valjd5ir@shell.armlinux.org.uk> (raw)
In-Reply-To: <CACRpkdZO6to2UsJ64FCYi3aOC79PEb9pxOBABBkgcmR_d82dYg@mail.gmail.com>
On Tue, Jul 09, 2019 at 02:17:58PM +0200, Linus Walleij wrote:
> On Mon, Jul 8, 2019 at 10:31 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> > -#define xip_iprefetch() do { asm volatile (".rep 8; nop; .endr"); } while (0)
> > +#define xip_iprefetch() do { \
> > + asm volatile ("nop; nop; nop; nop; nop; nop; nop; nop;"); \
> > +} while (0) \
>
> This is certainly an OK fix since we use a row of inline nop at
> other places.
>
> However after Russell explained the other nops I didn't understand I located
> these in boot/compressed/head.S as this in __start:
>
> .rept 7
> __nop
> .endr
> #ifndef CONFIG_THUMB2_KERNEL
> mov r0, r0
> #else
>
> And certainly this gets compiled, right?
>
> So does .rept/.endr work better than .rep/.endr, is it simply mis-spelled?
>
> I.e. s/.rep/.rept/g
> ?
>
> In that case we should explain in the commit that .rep doesn't work
> but .rept does.
According to the info pages for gas:
7.96 `.rept COUNT'
==================
Repeat the sequence of lines between the `.rept' directive and the next
`.endr' directive COUNT times.
So yes, ".rep" is mis-spelled, and it brings up the obvious question:
why isn't gas issuing an error for ".rep"? There is no mention of
".rep" in the manual.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
next prev parent reply other threads:[~2019-07-09 12:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-08 20:30 [PATCH] ARM: mtd-xip: work around clang/llvm bug Arnd Bergmann
2019-07-08 20:54 ` Nick Desaulniers
2019-07-09 8:41 ` Linus Walleij
2019-07-09 9:17 ` Russell King - ARM Linux admin
2019-07-09 11:48 ` Linus Walleij
2019-07-09 18:07 ` Nick Desaulniers
2019-07-09 18:40 ` Arnd Bergmann
2019-07-09 22:25 ` Russell King - ARM Linux admin
2019-07-10 8:33 ` Arnd Bergmann
2019-07-10 8:58 ` Russell King - ARM Linux admin
2019-07-09 12:17 ` Linus Walleij
2019-07-09 12:25 ` Russell King - ARM Linux admin [this message]
2019-07-09 18:11 ` Nick Desaulniers
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=20190709122550.nau44z32valjd5ir@shell.armlinux.org.uk \
--to=linux@armlinux.org.uk \
--cc=arnd@arndb.de \
--cc=clang-built-linux@googlegroups.com \
--cc=linus.walleij@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.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).