On Thu, May 24, 2001 at 03:42:56PM +0200, Maciej W. Rozycki wrote: > On Wed, 23 May 2001, Daniel Jacobowitz wrote: > > > The ll/sc constructs in the kernel use ".set noat" to inhibit use of $at, > > and proceed to use it themselves. This is fine, except for one problem: the > > constraints on memory operands are "o" and "=o", which means offsettable > > memory references. If I'm not mistaken, the assembler will (always?) > > turn these into uses of $at if the offset is not 0 - at least, it certainly > > seems to do that here (gcc 2.95.3, binutils 2.10.91.0.2). Just being honest > > with the compiler and asking for a real memory reference does the trick. > > Both "m" and "o" seem to be incorrect here as both are the same for MIPS; > "R" seems to be appropriate, OTOH. Still gcc 2.95.3 doesn't handle "R" > fine for all cases, but it works most of the time and emits a warning > otherwise. I can't comment on 3.0. They aren't the same for MIPS, though. I exhibit as evidence the fact that my patch fixed the problem I was seeing. I didn't know about 'R'; I suppose that it is more correct. 'm' at least is closer than 'o', though. If 'R' will behave correctly, could that be applied to CVS, then? > Note that if noat is in effect and at is to be used, gas should bail out > with an error. There is a bug, if it doesn't. It issues a warning, currently (2.10.91.0.2 - I think 2.11 behaves the same). -- Daniel Jacobowitz Debian GNU/Linux Developer Monta Vista Software Debian Security Team
