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Date:   Tue, 27 Jun 2023 19:24:14 +0200
From:   Petr =?UTF-8?B?VGVzYcWZw61r?= <petr@tesarici.cz>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Robin Murphy <robin.murphy@arm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Petr Tesarik <petrtesarik@huaweicloud.com>,
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        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Juergen Gross <jgross@suse.com>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Kees Cook <keescook@chromium.org>,
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        Roberto Sassu <roberto.sassu@huaweicloud.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: Re: [PATCH v3 1/7] swiotlb: make io_tlb_default_mem local to
 swiotlb.c
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On Tue, 27 Jun 2023 17:48:02 +0200
Christoph Hellwig <hch@lst.de> wrote:

> On Tue, Jun 27, 2023 at 01:30:06PM +0200, Petr Tesa=C5=99=C3=ADk wrote:
> > Xen is the only user of an "is SWIOTLB present" interface. IIUC Xen
> > needs bounce buffers for the PCI frontend driver, but if there is no
> > other reason to have a SWIOTLB, the system does not set up one at boot.=
 =20
>=20
> Please take a look at my "unexport swiotlb_active v2" series that
> unfortunately missed the 6.5 merge window waiting for reviews.

I noticed it, but it seems I missed the part which completely removes
pci_xen_swiotlb_init_late().

Then we're left only with a reference from xen_mm_init() in
arch/arm/xen/mm.c, and I believe this one can also be solved
differently.

Petr T