On Sun, 16 Jan 2005, Sam Ravnborg wrote:
>
> loadsegment take the pointer to second argument and cast it to unsigned
> int *. Using a properly sized variable as argument to loadsegment kills
> this warning.
I think the bug here is in "loadsegment".
I don't really see why it uses "m" in the first place, since you can
certainly move to a segment register from a reg too.
Afaik, that
"m" (*(unsigned int *)&(value)))
is likely from some old bogus code for totally historical reasons, and it
should likely just be
"rm" (value)
instead.
Of course, there may be some strange mis-use of the thing somewhere which
explains why the code does something that strange, and thus it might be
best to check that all users are ok.
> For this fix I wonder what happened to the upper bits in the old
> implmentation - they were undefined per definition.
They are ignored by the definition of the instruction, and the 32-bit
version (without a data size override) is selected just because it is
faster. Which may be why it does that strange cast too: to make sure that
the size of the operand matches (not that it should _matter_ for a memory
op).
Oh, and the "%0" in the asm descriptor should probably have the operand
character override for a full word, to make sure that the operand size
(when we use a register - where it _does_ matter) matches the "movl".
I think that means it should be "%k0" instead of "%0", ie something like
"movl %k0,%%" #seg "\n"
for the move itself, along with the fix for the strange value thing.
Willing to see if that works ok?
Linus
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