On Thu, 2015-12-03 at 01:24 +0000, Trent Piepho wrote: > The asm code to do the actual call into the kernel (or another > barebox) when compiled in thumb2 mode isn't necessary. gcc generates > a perfectly good calling sequence from a normal function pointer call. > If it didn't, the code in bootstrap_boot() that uses a function > pointer to jump to the 2nd stage barebox from an xloader wouldn't > work. The same commit that originally added this code also added thumb2_execute(), which is used by the go command in a thumb2 build. This doesn't seem necessary for the same reason as the code in start_linux. THUMB2 selects AEABI, which in turn turns on the aapcs abi, which requires interworking safe indirect calls. And again, the bootstrap code doesn't use a special call sequence so if it didn't work that would be broken too. The code for thumb2_execute() is also odd in that it subtracts one from argc, drops the 1st argv entry, and supplies zero for the first function argument. I.e., "go" in arm mode (and all non-arm arches) does this: func(argc - 1, &argv[1]); and in thumb2 mode does this: func(0, argc - 2, &argv[2]); I don't see why one would want this difference. _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
