2 ms·
Not quite: The 68000 didn't do this, but couldn't restart a page fault. The 68010 didn't either (but could restart a page fault). The 68020 and 030 did do th
by Taniwha 6y ago
Not quite:
The 68000 didn't do this, but couldn't restart a page fault.
The 68010 didn't either (but could restart a page fault).
The 68020 and 030 did do this horrible thing - doing Unix recursive signals was pretty hard if not impossible. And you couldn't copy this stuff to the user stack because it wasn't documented and so therefore you couldn't validate it when you pulled it back into the kernel.
The 68040 was sane again (and I presume subsequent 68ks)
Really this is part of the CISC vs. RISC thing - RISC instructions tend to have 1 side effect only, either they run to completion, or not at all, but CISC instructions can have multiple side effects - consider the infamous pdp11 instruction "mov -(pc), -(pc)" 3 side effects - 68k instructions are more complex multiple memory indirects, many possible faults, all that crud on the stack represents half done stuff