Bruce M Simpson wrote: > On Tue, Sep 21, 2004 at 02:41:42PM -0400, John Baldwin wrote: >>Umm, 0xa0000 is the start of Video RAM, so I sure hope the ACPI wake code >>doesn't try to write code into Video memory. The pmap_invalidate_page is >>certainly needed. > > This is more common than you'd think, by the way. The 0xA0000 range is > sometimes used as a place to hold 'hidden memory' used whilst servicing > an SMI; ie the pages are 'stolen' from main memory by the during BIOS > initialization using registers for APM/ACPI support in the chipset. > > Sometimes this is referred to as SMRAM or Systems Management Memory (SMM). > I posted some code just over a year ago illustrating how to access this > 'hidden segment' on the i440BX to the lists. Thanks, I work with SMIs a lot. :) The DDJ article is a good intro: http://www.rcollins.org/ddj/Jan97/Jan97.html -- NateReceived on Wed Sep 22 2004 - 15:57:47 UTC
This archive was generated by hypermail 2.4.0 : Wed May 19 2021 - 11:38:13 UTC