From: Christoph Hellwig <hch@infradead.org>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: John Ernberg <john.ernberg@actia.se>,
Juergen Gross <jgross@suse.com>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"iommu@lists.linux.dev" <iommu@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"imx@lists.linux.dev" <imx@lists.linux.dev>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 2/2] xen: swiotlb: Implement map_resource callback
Date: Wed, 7 May 2025 21:14:36 -0700 [thread overview]
Message-ID: <aBwvrLKD_VJapYkB@infradead.org> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2505071602570.3879245@ubuntu-linux-20-04-desktop>
On Wed, May 07, 2025 at 04:09:15PM -0700, Stefano Stabellini wrote:
> > This mapping is not for a RAM backed address. In the eDMA case for the
> > iMX8QXP the `phys` coming in here is the address of a register.
>
> Ok, this information is important :-)
>
> I am not certain whether the map_resource interface can only be called
> for MMIO addresses or if it can also be called for RAM-backed addresses
> with a size > PAGE_SIZE. In the latter case, we could run into the issue
> I was describing.
map_resource is intended for MMIO regions, although those could be >
PAGE_SIZE. It must not be called on RAM.
next prev parent reply other threads:[~2025-05-08 4:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-02 11:40 [PATCH 0/2] xen: swiotlb: 2 fixes SoCs w/o IOMMU (e.g. iMX8QXP) John Ernberg
2025-05-02 11:40 ` [PATCH 1/2] xen: swiotlb: Use swiotlb bouncing if kmalloc allocation demands it John Ernberg
2025-05-02 17:07 ` Stefano Stabellini
2025-05-08 15:21 ` Catalin Marinas
2025-05-02 11:40 ` [PATCH 2/2] xen: swiotlb: Implement map_resource callback John Ernberg
2025-05-02 17:20 ` Stefano Stabellini
2025-05-06 12:22 ` John Ernberg
2025-05-07 23:09 ` Stefano Stabellini
2025-05-08 4:14 ` Christoph Hellwig [this message]
2025-05-08 23:14 ` Stefano Stabellini
2025-05-09 7:48 ` John Ernberg
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