From: Robert Jarzmik <robert.jarzmik-GANU6spQydw@public.gmane.org>
To: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Cc: Russell King - ARM Linux
<linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>,
linux-arch <linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-api <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH 2/3] ARM: convert to generated system call tables
Date: Sat, 22 Oct 2016 22:23:54 +0200 [thread overview]
Message-ID: <87eg382kv9.fsf@belgarion.home> (raw)
In-Reply-To: <24632117.YsmPs86ri6@wuerfel> (Arnd Bergmann's message of "Fri, 21 Oct 2016 22:35:53 +0200")
Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org> writes:
> On Friday, October 21, 2016 4:48:56 PM CEST Russell King - ARM Linux wrote:
>> What's the point of the x32 mode?
>
> On x86, the motivation is faster code for most use cases that
> don't need a lot of memory, as the 64-bit opcodes have 16 registers
> rather than 8 in 32-bit mode but 32-bit pointers have lower
> cache footprint than 64-bit pointers.
For completness, the second point of x32 AFAIU is the IP-relative addressing
which is not available in standard 32 bit mode, which improves PIC code. For
simple not algorithmic code (think Android HAL for example) with many shared
libraries, it's better in the Hardware Abstraction Layer Libraries, instead of
the push-to-stack and pop register.
Cheers.
--
Robert
next prev parent reply other threads:[~2016-10-22 20:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1bwa6s-0004ZY-4k@rmk-PC.armlinux.org.uk>
[not found] ` <13702107.LdHY4HTXyY@wuerfel>
[not found] ` <20161019155325.GR1041@n2100.armlinux.org.uk>
2016-10-21 13:06 ` [PATCH 2/3] ARM: convert to generated system call tables Arnd Bergmann
2016-10-21 13:37 ` Russell King - ARM Linux
[not found] ` <20161021133708.GA1041-l+eeeJia6m9URfEZ8mYm6t73F7V6hmMc@public.gmane.org>
2016-10-21 15:18 ` Arnd Bergmann
2016-10-21 15:48 ` Russell King - ARM Linux
[not found] ` <20161021154856.GC1041-l+eeeJia6m9URfEZ8mYm6t73F7V6hmMc@public.gmane.org>
2016-10-21 16:48 ` Joseph Myers
[not found] ` <alpine.DEB.2.20.1610211641430.27636-9YEB1lltEqivcGRMvF24k2I39yigxGEX@public.gmane.org>
2016-10-21 16:57 ` Russell King - ARM Linux
2016-10-21 20:35 ` Arnd Bergmann
2016-10-22 20:23 ` Robert Jarzmik [this message]
2016-10-24 9:25 ` Geert Uytterhoeven
[not found] ` <CAMuHMdVy_h6Uss9bwVK5hGD42bXeEBcBsBDwCpx_eYnT9r+=Lw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-10-26 20:14 ` Robert Jarzmik
2016-10-24 9:29 ` Geert Uytterhoeven
2016-10-25 9:12 ` Michael Cree
2016-10-25 10:28 ` Arnd Bergmann
2016-10-25 17:03 ` Richard Henderson
2016-10-25 17:09 ` Geert Uytterhoeven
2016-10-26 7:04 ` Michael Cree
2016-10-26 9:12 ` bpf on Alpha [was Re: [PATCH 2/3] ARM: convert to generated system call tables] Michael Cree
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