On Monday 01 April 2013 03:19:43 Mike Frysinger wrote: > for ARM OABI, there is no such padding, and the proposed example is wrong > and will not work. > > for ARM EABI, the ABI requires that 64bit values be passed in register > pairs. since the kernel people wanted to avoid an assembly trampoline to > unpack the 64bit value with EABI, you have to call it as proposed: > syscall(readahead, fd, _pad, high32, low32) > > for MIPS, only the O32 ABI has this behavior. > > for PPC, only the 32bit ABI has this behavior. > > otherwise, i don't believe anyone else does this -- they just pass things > along in registers w/out padding. in random grepping of code bases (uClibc), i believe the xtensa arch also does 64bit register pair aligning. a cursory scan of the kernel seems to back this up. -mike
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