On Tue, Mar 20, 2012 at 3:04 PM, Stefan Kristiansson < [email protected]> wrote:
> On 03/20/2012 09:53 PM, Matthew Hicks wrote: > > On Tue, Mar 20, 2012 at 2:48 PM, Stefan Kristiansson < > [email protected]> wrote: > >> That's a truth with modification, isn't it? >> You proposed changing an implementation (or1200) not the ISA, >> and most felt it wasn't worth it since it could as well (and should) be >> handled in software. >> I don't think there was any discussion about unacceptable ABI breaks and >> changing ISAs. >> >> Stefan >> >> > http://lists.openrisc.net/pipermail/openrisc/2011-December/000533.html where > I first propose changing the ISA as well as the implementation. > > > > Ah, yes you did, I stand corrected :) > > But still, changing the specification to define r0 to be hardwired to 0 > or that it _has_ to be regarded as a nop is probably a too big of a change, > clarifying that writing to r0 should have no side effects > (except possibly writing a nonzero value to it) is another story. > > Stefan > I am confused. So are you saying that the ISA say that only writing a non-zero value to r0 be undefined? ---Matthew Hicks
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