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Date: Mon, 11 Nov 2024 07:39:32 +0100
From: Christoph Hellwig <hch@lst.de>
To: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Jason Gunthorpe <jgg@ziepe.ca>, Robin Murphy <robin.murphy@arm.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	Leon Romanovsky <leonro@nvidia.com>,
	Keith Busch <kbusch@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	=?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-rdma@vger.kernel.org, iommu@lists.linux.dev,
	linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org,
	kvm@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v1 04/17] dma-mapping: Add check if IOVA can be used
Message-ID: <20241111063932.GC23992@lst.de>
References: <cover.1730298502.git.leon@kernel.org> <9515f330b9615de92a1864ab46acbd95e32634b6.1730298502.git.leon@kernel.org> <5ea594b3-7451-4553-92c1-2590c8baef20@linux.dev>
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On Sun, Nov 10, 2024 at 04:09:11PM +0100, Zhu Yanjun wrote:
>> +
>> +/*
>> + * Use the high bit to mark if we used swiotlb for one or more ranges.
>> + */
>> +#define DMA_IOVA_USE_SWIOTLB		(1ULL << 63)
>
> A trivial problem.
> In the above macro, using BIT_ULL(63) is better?

No, and can people please stop suggesting it?  That macro is so fucking
pointless that it's revolting,