Re: [linuxsh-dev] Re: bad alignment fixup

[Philipp R. <pr...@pa...>]

On Thu, Nov 23, 2000 at 05:55:40PM +0000, David Woodhouse wrote:
> 
> pr...@pa... said:
[dropped the network stack discussion, as it's offtopic here]

> pr...@pa... said:
> >  Do it correctly or don't do it at all.  "We emulate all unaligned
> > memory accesses except 3 or 4 we didn't bother with" isn't a sensible
> > rule.
> 
> It's correct, or certainly getting there. It's not _complete_ but I'm sure

generating SEGV for unknown unaligned instructions isn't correct.

> someone will contribute the missing insns, even if _we_ don't actually get 
> round to it.

I think that would add prohibitively large amounts of code, and quite
possibly new security holes.

> pr...@pa... said:
> >  which makes using a syscall return value constant confusing.
> 
> It doesn't confuse me. Standard error numbers are used _internally_ 
> throughout the kernel, even where they're not actually being returned to 
> userspace.

I can remember no case where it's impossible for userspace to see the error,
except for module_init until a few versions ago. 

> Are there other causes of address error in SH-[45]?

unprivileged accesses to 0x80000000 .. 0xffffffff