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Date: Tue, 12 Aug 2014 10:09:49 +0100
From: David Vrabel <david.vrabel@citrix.com>
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To: Yijing Wang <wangyijing@huawei.com>, Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [Xen-devel] [RFC PATCH 01/20] x86/xen/MSI: Eliminate
 arch_msix_mask_irq() and arch_msi_mask_irq()
References: <1407828373-24322-1-git-send-email-wangyijing@huawei.com>
 <1407828373-24322-2-git-send-email-wangyijing@huawei.com>
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Cc: linux-mips@linux-mips.org, linux-ia64@vger.kernel.org,
 linux-pci@vger.kernel.org, Xinwei Hu <huxinwei@huawei.com>, "H. Peter
 Anvin" <hpa@zytor.com>, sparclinux@vger.kernel.org, linux-s390@vger.kernel.org,
 Russell King <linux@arm.linux.org.uk>, Joerg Roedel <joro@8bytes.org>,
 x86@kernel.org, Sebastian Ott <sebott@linux.vnet.ibm.com>,
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 Arnd Bergmann <arnd@arndb.de>, Marc Zyngier <marc.zyngier@arm.com>,
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 Wuyun <wuyun.wu@huawei.com>, linuxppc-dev@lists.ozlabs.org,
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On 12/08/14 08:25, Yijing Wang wrote:
> Commit 0e4ccb150 added two __weak arch functions arch_msix_mask_irq()
> and arch_msi_mask_irq() to fix a bug found when running xen in x86.
> Introduced these two funcntions make MSI code complex. This patch
> reverted commit 0e4ccb150 and add #ifdef for x86 msi_chip to fix this
> bug for simplicity. Also this is preparation for using struct
> msi_chip instead of weak arch MSI functions in all platforms.
[...]
>  static struct irq_chip msi_chip = {
>  	.name			= "PCI-MSI",
> +#ifdef CONFIG_XEN
> +	.irq_unmask		= nop_unmask_msi_irq,
> +	.irq_mask		= nop_mask_msi_irq,
> +#else
>  	.irq_unmask		= unmask_msi_irq,
>  	.irq_mask		= mask_msi_irq,
> +#endif

No.  CONFIG_XEN kernels can run on Xen and bare metal so this must be a
runtime option.

David