Eric Decker <cire831 <at> gmail.com> writes: > > On Mon, Aug 8, 2011 at 10:57 PM, Alex Stefan > <alexandru.stefan <at> cloudbit.ro>wrote: > > > > > As I said, seems like a very good idea, but there's one thing I don't > > understand. Why do you need the 'indirect jumping zone'. Why wouldn't it be > > possible to program the vector in bootvect to jump directly to the > > interrupt > > vector table of the application? Except, of course, the reset vector which > > will > > still point to the bootloader. > > > > The vector table is a table and not a table of instructions that get > executed. > > So the bootload has its vector table as the main table and it knows where > the other vector table is. So it acts as an intermediary and hence the > extra level of indirection which costs you a few more cycles in the > interrupt path. > > The fastest way to program this at the expense of space is to have the > jumptable which has the br instructions. The real vector table if the boot > loader doesn't want a vector points at the entry in the jumptable to kicks > to the main vector. >
Ok, but why can't we have something like: 0x5C00-0xFB7F application flash 0xFB80-0xFBFF applcation interrupt vector table 0xFC00-0xFE7F bootloader (NOT)0xFE80-0xFF7F jumptable (br &0xFB80; br &0xFB82;...) 0xFF80-0xFFFF 'real' vector table, pointing to bootloader start or jumptable. (0xFB80, 0xFB84, 0xFB88,...) instead of: 0x5C00-0xFB7F application flash 0xFB80-0xFBFF applcation interrupt vector table 0xFC00-0xFE7F bootloader 0xFE80-0xFF7F jumptable (br &0xFB80; br &0xFB82;...) 0xFF80-0xFFFF 'real' vector table, pointing to bootloader start or jumptable. (0xFE80, 0xFE84, 0xFE88,...) Thanks, Alex > > eric > ------------------------------------------------------------------------------ uberSVN's rich system and user administration capabilities and model configuration take the hassle out of deploying and managing Subversion and the tools developers use with it. Learn more about uberSVN and get a free download at: http://p.sf.net/sfu/wandisco-dev2dev _______________________________________________ Mspgcc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mspgcc-users
