On Tue, 22 May 2001, Jun Sun wrote: > I took a look of MIPS ABI in system V and found that the spec only specifies > this extended call in C prototype: > > int _test_and_set(int *p, int v); > > It seems perfectly legal for us to add one more argument to store the return > value while still have the function returns error. Of course, doing that will > break binary compatibility. We have _test_and_set() in the library. Implementing a clean underlying _test_and_set() syscall is very high on my to-do list -- lack of time prevents me from finishing it, unfortunately. There is no point to mess with sysmips() any further, I think. The library's _test_and_set() only calls sysmips() if the library was compiled for ISA I systems. As I guess from reports on the list, ISA I systems are a minority, mostly DECstations and possibly a few embedded systems. Most people have ISA II+ and they do not need to call any syscall from _test_and_set() at all. For ISA II+ systems the library implements _test_and_set() in the userland, using ll/sc appropriately. Anyone having ISA II+ systems only, please do yourself a favour and set "-mips2" (or maybe even "-mips3") somewhere in your CFLAGS for all compilations -- not only you'll get better optimized binaries, but you'll get rid of this sysmips() problem as well. > Otherwise, I think Flo's patch is the best fix to satisfy the spec and binary > compatibility although it is a little clunky. I'll have yet to look at the patch, but what I think is, we should get sysmips() work as defined by the original spec (or as reverse-engineered, as the real spec seems to be out of reach). Everything else belong to a separate implementation. Binary compatibility is not a necessity here. The only sysmips() client is glibc at the moment, and it can be updated to use a new syscall at any time. In short: let's leave sysmips() semantics alone. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
