Re: [PATCH 6.10 000/809] 6.10.3-rc3 review

[John David Anglin]

On 2024-08-08 10:59 a.m., Guenter Roeck wrote:
> > Let's wait for PARISC people to run it on actual hardware.
>
> Agreed. I suspect that there is a carry or upper 32 bit of a register not
> handled properly, but I have no idea where that might be or why that would
> only be seen if the div functions are located in a certain address range.
I'm doubtful there's a coding issue in $$divoI.  The routine was written by HP and
it's used on both HP-UX and Linux.  The routine can be found in libgcc/config/pa/milli64.S

The routine can trap:
   Divide by zero is trapped.
   Divide of -2**31 by -1 is trapped for $$divoI but not for $$divI.

$$divoI is a millicode routine.  Not sure what calls it.  gcc doesn't call it.  gcc uses $$divI.

It appears you are testing a 64-bit kernel.  There might be issues calling millicode routines
when branch distance exceeds approximately 4 MB.  Millicode routines have a special
calling sequence.  You could try building kernel with -mlong-calls. Kernel will get bugger
and slower with this option.

Dave

--
John David Anglin  dave.anglin@xxxxxxxx