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charset="us-ascii" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-OriginatorOrg: outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SN6PR02MB4157.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-Network-Message-Id: 20262499-b887-4229-d8e6-08dc5fbbd2be X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-originalarrivaltime: 18 Apr 2024 15:25:47.8651 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-Transport-CrossTenantHeadersStamped: CYYPR02MB9927 From: Matthew Wilcox Sent: Thursday, April 18, 2024 7= :29 AM >=20 > On Thu, Apr 18, 2024 at 06:52:13AM -0700, mhkelley58@gmail.com wrote: > > There's currently no documentation for the swiotlb. Add documentation > > describing usage scenarios, the key APIs, and implementation details. > > Group the new documentation with other DMA-related documentation. >=20 > This is really well written. Thank you. One minor nit below. >=20 > > +Usage Scenarios > > +--------------- > > +The swiotlb was originally created to handle DMA for devices > > +with addressing limitations. As physical memory sizes grew > > +beyond 4 Gbytes, some devices could only provide 32-bit DMA > > +addresses. By allocating bounce buffer memory below the 4 Gbyte >=20 > I'd prefer GiB to Gbytes; we might also prefer GB, Gigabyte or Gibibyte, > but Gbytes seems wrong. Good point. I'll update sizes throughout to use the correct terminology. Michael >=20 > You've written a lot here, and I'm not an expert on swiommu, but nothing > else leapt out at me.