From: Nathan_Lynch@mentor.com (Lynch, Nathan)
To: linux-arm-kernel@lists.infradead.org
Subject: [VDSO]: vdso_test failing on arm 32 bit
Date: Thu, 8 Feb 2018 16:11:07 +0000 [thread overview]
Message-ID: <1518106267799.61329@mentor.com> (raw)
In-Reply-To: <CAOuPNLgj8c0a1gDESQDatoa4GU_PYu8TK1NJ0KKkVfjW7zvsdA@mail.gmail.com>
> I commented the device tree reading property:
> arm,cpu-registers-not-fw-configured , from the arch/arm/kernel/vdso.c
Don't do that, please. The presence of that property indicates that the counter is not suitable for use by the OS. There is nothing we can do in Linux to make the VDSO useful on this system; that is why it gets disabled at runtime.
The timing measurements you get are likely tainted by garbage results from the VDSO itself.
WARNING: multiple messages have this Message-ID (diff)
From: "Lynch, Nathan" <Nathan_Lynch@mentor.com>
To: Pintu Kumar <pintu.ping@gmail.com>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>,
"david.brown@linaro.org" <david.brown@linaro.org>,
open list <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [VDSO]: vdso_test failing on arm 32 bit
Date: Thu, 8 Feb 2018 16:11:07 +0000 [thread overview]
Message-ID: <1518106267799.61329@mentor.com> (raw)
In-Reply-To: <CAOuPNLgj8c0a1gDESQDatoa4GU_PYu8TK1NJ0KKkVfjW7zvsdA@mail.gmail.com>
> I commented the device tree reading property:
> arm,cpu-registers-not-fw-configured , from the arch/arm/kernel/vdso.c
Don't do that, please. The presence of that property indicates that the counter is not suitable for use by the OS. There is nothing we can do in Linux to make the VDSO useful on this system; that is why it gets disabled at runtime.
The timing measurements you get are likely tainted by garbage results from the VDSO itself.
next prev parent reply other threads:[~2018-02-08 16:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-12 16:19 [VDSO]: vdso_test failing on arm 32 bit Pintu Kumar
2017-12-12 16:19 ` Pintu Kumar
2017-12-12 16:26 ` Russell King - ARM Linux
2017-12-12 16:26 ` Russell King - ARM Linux
[not found] ` <1513098352501.51185@mentor.com>
[not found] ` <20171212172034.GC10595@n2100.armlinux.org.uk>
[not found] ` <CAOuPNLiTf040ZOyEroq4oy=5Bz1LScmE-vpR3xdjXBGuCKcxMA@mail.gmail.com>
[not found] ` <20171213111718.GJ10595@n2100.armlinux.org.uk>
[not found] ` <CAOuPNLgM8OxP8cV9goAUDtXgxjhcfoe27M0Q=Ty1BVAPD5aipQ@mail.gmail.com>
[not found] ` <20171213171530.GM10595@n2100.armlinux.org.uk>
[not found] ` <1513186632784.96495@mentor.com>
[not found] ` <20171213173956.GN10595@n2100.armlinux.org.uk>
[not found] ` <CAOuPNLgZL0N0OuTUEVR6vFjykBtLeR+t0pvn3FSKsA4UqG-UGQ@mail.gmail.com>
[not found] ` <20171214102148.GO10595@n2100.armlinux.org.uk>
2018-02-08 7:10 ` Pintu Kumar
2018-02-08 7:10 ` Pintu Kumar
2018-02-08 16:11 ` Lynch, Nathan [this message]
2018-02-08 16:11 ` Lynch, Nathan
2018-02-08 16:53 ` Pintu Kumar
2018-02-08 16:53 ` Pintu Kumar
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