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From: Thomas Gleixner <tglx@linutronix.de>
To: Daniel Drake <drake@endlessm.com>
Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
	x86@kernel.org, linux-wireless@vger.kernel.org,
	ath9k-devel@qca.qualcomm.com, linux@endlessm.com
Subject: Re: [PATCH] PCI MSI: allow alignment restrictions on vector allocation
Date: Mon, 2 Oct 2017 18:19:36 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1710021817500.9529@nanos> (raw)
In-Reply-To: <alpine.DEB.2.20.1710021540030.2185@nanos>

On Mon, 2 Oct 2017, Thomas Gleixner wrote:
> On Mon, 2 Oct 2017, Daniel Drake wrote:
>   2) The affinity setting of straight MSI interrupts (w/o remapping) on x86
>      requires to make the affinity change from the interrupt context of the
>      current active vector in order not to lose interrupts or worst case
>      getting into a stale state.
> 
>      That works for single vectors, but trying to move all vectors in one
>      go is more or less impossible, as there is no reliable way to
>      determine that none of the other vectors is on flight.
> 
>      There might be some 'workarounds' for that, but I rather avoid that
>      unless we get an official documented one from Intel/AMD.

Thinking more about it. That might be actually a non issue for MSI, but we
have that modus operandi in the current code and we need to address that
first before even thinking about multi MSI support.

Thanks,

	tglx

  reply	other threads:[~2017-10-02 16:19 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-25  4:11 [PATCH] PCI MSI: allow alignment restrictions on vector allocation Daniel Drake
2017-09-26 20:32 ` kbuild test robot
2017-09-27 15:28 ` Thomas Gleixner
2017-10-02  8:57   ` Daniel Drake
2017-10-02 14:38     ` Thomas Gleixner
2017-10-02 16:19       ` Thomas Gleixner [this message]
2017-10-03 21:07         ` Thomas Gleixner
2017-10-03 21:34           ` Bjorn Helgaas
2017-10-03 21:46             ` Thomas Gleixner
2017-10-05  4:23       ` Daniel Drake
2017-10-05 10:13         ` Thomas Gleixner

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