linux-kernel - Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151124103715.GY8644@n2100.arm.linux.org.uk>
Date:	Tue, 24 Nov 2015 10:37:16 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Peter Maydell <peter.maydell@...aro.org>,
	Måns Rullgård <mans@...sr.com>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Christopher Covington <cov@...eaurora.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library
 functions

On Mon, Nov 23, 2015 at 04:13:06PM -0800, Stephen Boyd wrote:
> On 11/23, Arnd Bergmann wrote:
> > 
> > Ok, thanks for the confirmation.
> > 
> > Summarizing what we've found, I think we can get away with just
> > introducing two Kconfig symbols ARCH_MULTI_V7VE and CPU_V7VE.
> > Most CPUs fall clearly into one category or the other, and then
> > we can allow LPAE to be selected for V7VE-only build but not
> > for plain V7, and we can unconditionally build the kernel with
> > 
> > arch-$(CONFIG_CPU_32v7VE)  = -D__LINUX_ARM_ARCH__=7 $(call cc-option,-march=armv7ve,-march=armv7-a -mcpu=cortex-a15)
> > 
> 
> This causes compiler spew for me:
> 
>   warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch
> 
> Removing -march=armv7-a from there makes it quiet.
> 
> Also, it's sort of feels wrong to have -mcpu in a place where
> we're exclusively doing -march. Perhaps the fallback should be
> bog standard -march=armv7-a? (or the fallback for that one
> "-march=armv5t -Wa$(comma)-march=armv7-a")?

How it was explained to me years ago is that -march selects the
instruction set, -mtune selects the instruction scheduling, and -mcpu
selects both.

-- 
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/