On Friday, August 19, 2016 06:48:10 PM Al Stone wrote: > Several strange things were found while prototyping a way to correctly > report whether or not an IORT is needed by an arm64 platform. What the > prototype needed to do was iterate over the MADT subtables and look for > certain types of subtable, count how many there were by type, and capture > some info about some of the subtables. > > When I first read through the acpi_parse_entries_array() function, the > comments seemed to describe precisely what I needed to do. However, what > I found in trying to use the function is that that is not exactly how it > works. > > So, the first patch fixes the counts of subtable types found so they are > correct. Fortunately, nothing has relied on them being correct in the > past, just non-zero or not. This has also been noted by Baoquan He in a > patch he recently submitted. > > The second patch fixes a problem where iterating over the subtables would > end earlier than necessary, again throwing off the counts; in this case, > I only needed to know how many of certain types of subtables were present, > but would never be able to get to a complete count. > > The third patch removes part of a message that always reported an incorrect > value for the number of subtables skipped when there's a limit. It always > reported zero, so it's never really been useful. > > Longer term, I would like to simplify the way MADT and other ACPI tables > with subtables are parsed; mostly, I want to get rid of the need for using > file scoped variables. The acpi_parse_entries_array() function can be a > good basis to build upon, as long as it works as expected. > > Changes since v1: > -- Much rewrite of the cover letter and changelogs to make sure the > motivation for the changes was captured (Rafael) > -- Verified that the changes in semantics for the function are harmless; > direct calls, parents/grandparents/.. of the direct calls were checked > to make sure they did not depend on the current behavior in such a way > as to break them with these changes (Rafael) > -- Patch 3/3 was simplified; on further investigation, should additional > callbacks be made to get the total skipped, there could be side effects > or dependencies between callbacks that would make the original plan of > iterating over all callbacks risky, for very little value (Rafael) > > Al Stone (3): > ACPI: fix incorrect counts returned by acpi_parse_entries_array() > ACPI: fix acpi_parse_entries_array() so it traverses all subtables > ACPI: do not report the number of entries ignored by > acpi_parse_entries() All applied. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
