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| author | Jiri Kosina <jkosina@suse.cz> | 2023-11-01 02:07:35 +0300 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2023-11-01 02:07:35 +0300 |
| commit | 20cd569d7ee8fce24e8753f0f43af6c420557b1f (patch) | |
| tree | f559cfda594846795aa51c99d96f92d8c912851a /arch/parisc/include/asm/shmparam.h | |
| parent | 62cc9c3cb3ec1bf31cc116146185ed97b450836a (diff) | |
| parent | eeebfe6259ba2d5b0980eb7b0df384eb77e9e4f5 (diff) | |
| download | linux-20cd569d7ee8fce24e8753f0f43af6c420557b1f.tar.xz | |
Merge branch 'for-6.7/config_pm' into for-linus
- #ifdef CONFIG_PM removal from HID code (Thomas Weißschuh)
Diffstat (limited to 'arch/parisc/include/asm/shmparam.h')
| -rw-r--r-- | arch/parisc/include/asm/shmparam.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/parisc/include/asm/shmparam.h b/arch/parisc/include/asm/shmparam.h index 74f74e4d35b7..5a95b0f62b87 100644 --- a/arch/parisc/include/asm/shmparam.h +++ b/arch/parisc/include/asm/shmparam.h @@ -2,6 +2,21 @@ #ifndef _ASMPARISC_SHMPARAM_H #define _ASMPARISC_SHMPARAM_H +/* + * PA-RISC uses virtually indexed & physically tagged (VIPT) caches + * which has strict requirements when two pages to the same physical + * address are accessed through different mappings. Read the section + * "Address Aliasing" in the arch docs for more detail: + * PA-RISC 1.1 (page 3-6): + * https://parisc.wiki.kernel.org/images-parisc/6/68/Pa11_acd.pdf + * PA-RISC 2.0 (page F-5): + * https://parisc.wiki.kernel.org/images-parisc/7/73/Parisc2.0.pdf + * + * For Linux we allow kernel and userspace to map pages on page size + * granularity (SHMLBA) but have to ensure that, if two pages are + * mapped to the same physical address, the virtual and physical + * addresses modulo SHM_COLOUR are identical. + */ #define SHMLBA PAGE_SIZE /* attach addr a multiple of this */ #define SHM_COLOUR 0x00400000 /* shared mappings colouring */ |