Handles from a DSDT are in fact permanent. Once a SSDT is unloaded, however, those handles are invalid. We are considering making these handles "real" handles instead of simply pointers to catch the use of an invalid handle. > -----Original Message----- > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- > owner@xxxxxxxxxxxxxxx] On Behalf Of Henrique de Moraes Holschuh > Sent: Wednesday, February 07, 2007 11:44 AM > To: linux-acpi@xxxxxxxxxxxxxxx > Cc: ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: Caching the results of acpi_get_handle() in a driver: is it > valid? > > The code I inherited in ibm-acpi does heavy caching of acpi_get_handle() > results. It stores the results of acpi_get_handle() for a number of nodes > at module init, and uses the stored results during its lifetime. > > Is that a valid use of the handles returned by acpi_get_handle()? In > particular, what happens to handlers when a SSDT gets loaded or unloaded > at > runtime? Do handles that came from the DSDT change? What if the handler > was to a node in the SSDT being unloaded? What if the handler is > overriden > by a new loaded SSDT? > > While the vast majority of the handlers ibm-acpi caches are in the DSDT > and > very unlikely to change through a SSDT load, I'd still like to make sure > the > driver is doing the right thing... > > PS: not caching the results is always possible, but that will mean various > calls to acpi_get_handle() per second. > > -- > "One disk to rule them all, One disk to find them. One disk to bring > them all and in the darkness grind them. In the Land of Redmond > where the shadows lie." -- The Silicon Valley Tarot > Henrique Holschuh > - > 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 - 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
