From: Nick Ewalt <nicholasewalt@xxxxxxxxxx> Add that number of page table entries and extended address bit offset are configurable. Update example virtual address format to be more consistent with typical usage. Signed-off-by: Nick Ewalt <nicholasewalt@xxxxxxxxxx> Signed-off-by: Todd Poynor <toddpoynor@xxxxxxxxxx> --- drivers/staging/gasket/gasket_page_table.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/staging/gasket/gasket_page_table.c b/drivers/staging/gasket/gasket_page_table.c index c2fbab74194f8..5b398b7ba81d3 100644 --- a/drivers/staging/gasket/gasket_page_table.c +++ b/drivers/staging/gasket/gasket_page_table.c @@ -10,10 +10,18 @@ * * This file assumes 4kB pages throughout; can be factored out when necessary. * - * Address format is as follows: + * There is a configurable number of page table entries, as well as a + * configurable bit index for the extended address flag. Both of these are + * specified in gasket_page_table_init through the page_table_config parameter. + * + * The following example assumes: + * page_table_config->total_entries = 8192 + * page_table_config->extended_bit = 63 + * + * Address format: * Simple addresses - those whose containing pages are directly placed in the * device's address translation registers - are laid out as: - * [ 63 - 40: Unused | 39 - 28: 0 | 27 - 12: page index | 11 - 0: page offset ] + * [ 63 - 25: 0 | 24 - 12: page index | 11 - 0: page offset ] * page index: The index of the containing page in the device's address * translation registers. * page offset: The index of the address into the containing page. @@ -21,7 +29,7 @@ * Extended address - those whose containing pages are contained in a second- * level page table whose address is present in the device's address translation * registers - are laid out as: - * [ 63 - 40: Unused | 39: flag | 38 - 37: 0 | 36 - 21: dev/level 0 index | + * [ 63: flag | 62 - 34: 0 | 33 - 21: dev/level 0 index | * 20 - 12: host/level 1 index | 11 - 0: page offset ] * flag: Marker indicating that this is an extended address. Always 1. * dev index: The index of the first-level page in the device's extended -- 2.19.0.605.g01d371f741-goog _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
