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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?sKqTKJlrQus/vPBD6TqqBlXbTl6slhaJ1BL2f5NaJrx8EvLTDV5iJwXjt/QD?= =?us-ascii?Q?nVpe6xOB1TeiKnN4+qPPZAeQNM7FDK3y0ut9+sjFteQ95P11SC1DPogZ2Qnv?= =?us-ascii?Q?SGSTuxhLXn+DVU3GencQAeuTFTE1aUNmCUirveiaR0227p+WreRK9Gz6lLdC?= =?us-ascii?Q?e7v3pL5NPXBuMsceT6bz9DKuVqinRziO2wJI50HUbiEu5g5D5I+ysqkuG3Bj?= =?us-ascii?Q?wGcLqOnxiZqs4/RgDrIJlcz9ovF9uUUeb4jGih052ciqzbUIAQqHVyXqVi3d?= =?us-ascii?Q?eNClkXYqh10kvN25IK6CCJuXGsQjubFAgk5bz5jFY1VE8iTwERNA19D/jYZX?= =?us-ascii?Q?/5BQeHB8lwPTUiPCuB5O2mhzyN8tkqLNVZjuOMh5fwQZCvb3hAu1303Z4W8T?= =?us-ascii?Q?9tRz4xFQTH7WA3NEqXlzLHzls1ETrxjkD1ukUg9VQhoxm7UHuNaUufPty4o+?= =?us-ascii?Q?6dVjoeW+FDd/TtKJqdKlfrmS1tvKaaHrUX1EtlwPlEyvWsT4WpIlB5t4UncP?= =?us-ascii?Q?hSRwZu+gck00B8gC/a4pUk7y6+QyACvN5aHckquWxYVp2WMEK7FIQytcp78j?= =?us-ascii?Q?nrgo0fi+OgjCESiOYBmeGoUq8z1syTo5S0GYLsbKnSrRBNLqAh1B7RJSH11U?= =?us-ascii?Q?IPZ25TgRHaus92VBqhyEnzMqYFuRIx1SJpZcbLXkcimAo3kqMkg9UZhC4EWB?= =?us-ascii?Q?NXDUOK1qxmzSwM/EgzmjOSpZdRzyFRjzMuQ5ikFURJk3Je6sZq7PfAIqDB6Q?= =?us-ascii?Q?sZYdkJ8cAjTAxUF1PLEkrbBKRvJfZAVOTdZxl41XVVllGuYKhC6ziRGXa/Qm?= =?us-ascii?Q?oCp6aO/c1Xd2Zk271hjKUMSVrrDHsUNgYC7vA/y3hL7C0t3W4CRSZYP0SzHx?= =?us-ascii?Q?GruXBOs1Q4qjKaw1cbBrOB4bLusWcHvPt7LW88iYSDnOA3zLOLOGkB/HBYsU?= =?us-ascii?Q?iS6Q5SscfwGodOzRsbAtDwa26oZJASt7poyzu47F7WnVcL7FTjqGiZw5+a3H?= =?us-ascii?Q?FPfmVwyBiZmVQfh2/d3aXywJe+jFxNbfIv8Yq9psAHjZzqOMg3KMaORnHBBq?= =?us-ascii?Q?7sRuG30ZPGez0YlTc3+LbesN7bcUj2gc4wNKaTMUvv0hdpNA4xHjeixZXlUl?= =?us-ascii?Q?IkJwFkjFBVL6fIac0A7Sz9cf3Seaq6uJUaY/v/jQKGCiWoLWfqYwBQwqsFji?= =?us-ascii?Q?F3xRHAAJ0x/VEVg23FWMwbVk7nPm3ULdhFol5H/0Ow9J65LZmb/z+fVA+3aT?= =?us-ascii?Q?TvtqCa3nIOUBfLQZVt7X8+LdvAxhjiH+Q5cvQ1ZaSIRc+YshkatajZwlphAj?= =?us-ascii?Q?Rkzt/kBH1AqZDhuWKC26p7UzjYryydgNkVvmb6mp60tgSl/+iy0AvdhKZbup?= =?us-ascii?Q?kP0UO5RZL4SP3Rapj/xaT+zSjbk6UPciCKY6Xj4nQPmjYLgue2UBXkaqZv0W?= =?us-ascii?Q?8JyIGAhTyB1ZUqegAbWz5BTlVc866mHyDFxlVAKQXeYVOB7TzIqY0xtF+0y6?= =?us-ascii?Q?taLp31TAzoYnr01F0eLwYXj2pzYhenczfjWXfkz8gHEwEDQTts+S1s8ObDZy?= =?us-ascii?Q?UkE4DvAJ4JK/eWDlYa31BRginuoVk7yL65fGLNmERjRousPVjNM+T2nKXDNy?= =?us-ascii?Q?h3ciunw7Sp5qnkbTItNS6YgBjwo/I8O0ByyUrbBnurlETD798yFbkuitxq6k?= =?us-ascii?Q?La/40raj6dfZN6rW1UXOq9tMWxZ8MWwQv36EWfmLHrh3fXDK?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 34b79c46-7393-4908-da0f-08de3f22086f X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Dec 2025 17:14:13.7328 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: ev8Ou01oH8lj5dV3BwI+AEgC1imFHHgHEVaoI4KiZ4IFgrVmGFvzUffSO45MsdLz X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9100 On Fri, Dec 19, 2025 at 05:15:58PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > As Jason Gunthorpe noticed, supporting VIVT caches adds some complications > to highmem that can be avoided these days: > > While all ARMv4 and ARMv5 CPUs use virtually indexed caches, they no > longer really need highmem because we have practically discontinued > support for large-memory configurations already. The only machines I > could find anywhere for memory on ARMv5 are: > > - The Intel IOP platform was used on relatively large memory > configurations but we dropped kernel support in 2019 and 2022, > respectively. > > - The Marvell mv78xx0 platform was the initial user of Arm highmem, > with the DB-78x00-BP supporting 2GB of memory. While the platform > is still around, the only remaining board file is for > Buffalo WLX (Terastation Duo), which has only 512MB. > > - The Kirkwood platform supports 2GB, and there are actually boards > with that configuration that can still work. However, there are > no known users of the OpenBlocks A7, and the Freebox V6 is already > using CONFIG_VMSPLIT_2G to avoid enabling highmem. > > Remove the Arm specific portions here, making CONFIG_HIGHMEM conditional > on modern caches. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Arnd Bergmann > --- > arch/arm/Kconfig | 1 + > arch/arm/configs/gemini_defconfig | 1 - > arch/arm/configs/multi_v5_defconfig | 1 - > arch/arm/configs/mvebu_v5_defconfig | 1 - > arch/arm/include/asm/highmem.h | 56 ++--------------------------- > arch/arm/mm/cache-feroceon-l2.c | 31 ++-------------- > arch/arm/mm/cache-xsc3l2.c | 47 +++--------------------- > arch/arm/mm/dma-mapping.c | 12 ++----- > arch/arm/mm/flush.c | 19 +++------- > 9 files changed, 16 insertions(+), 153 deletions(-) This looks great, but do you think there should be a boot time crash if a VIVT and HIGHMEM are enabled, just incase? Jason