Hi! For a long time now, the agpgart module has been creating illegal mapping aliases, since the user-space mappings of the pages in the gart are usually write-combined, whereas the kernel linear mapping of the same pages are uc for x86, and may even be wb for some architectures.
In order to fix this, and to facilitate fast insertion and removal of pages into / from the gart I'd like to disable all default kernel mappings for those pages, which would in effect, make them behave as highmem pages from our point of view. As prevously discussed, the x86 set_memory_xxx() interface wasn't suitable for this, since it handles only a single mapping, and the pages may have more than one default kernel mapping. But it turns out that there is an interface that does exactly this. kernel_map_pages(). But it is only available with CONFIG_DEBUG_PAGEALLOC. I'd like to make that function exported by default, but with some minor alterations as the original functions does some debug checks as well, that aren't desirable for the purpose mentioned above: As with highmem pages, if the driver sets up user-space mappings with non-standard caching attributes, those mappings need to be killed at suspend time, since the suspend code would otherwise create temporary incompatible mappings. On x86 this all would probably work fine. Does kernel_map_pages() work identically on other architectures? Specifically: Will it always work with a 4K page granularity? Thanks, Thomas /* * Enable / disable all default kernel mappings of a number of contigous pages. * This is an alias for kernel_map_pages() but with debug checks removed. */ int kernel_default_map_pages(struct page *page, int numpages, int enable); EXPORT_SYMBOL(kernel_default_map_pages); /* * Enable / disable all default kernel mappings of a number of single pages. */ int kernel_default_map_pagearray(struct page **pages, int numpages, int enable); EXPORT_SYMBOL(kernel_default_map_pagearray); ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
