Re: Athlon/VIA Kernel Experimentation (mmx.c)

[Seth Goldberg <bergsoft@home.com>]

 Doh. I feel like a moron.  Thanks.. will do...

 --S


Brian Gerst wrote:
> 
> Seth Goldberg wrote:
> >
> > Hi,
> >
> >   I implemented a small check loop at the end of the fast_page_copy
> > routine in mmx.c for the Athlon.  Booting the resulting kernel
> > yields an interesting result. Every single time, the kernel
> > panics RIGHT AFTER it frees unused kernel memory from bootup.
> > I encourage those of you with the same problem to try this and report
> > when it panics.
> >
> > Here is my patch to mmx.c: (sorry about the long lines)
> > -----------------------------------------------------cut here
> > diff -r linux-ref/arch/i386/lib/mmx.c linux/arch/i386/lib/mmx.c
> > 204a205,216
> > >
> > >       {
> > >               register int x = 0;
> > >               /* do mem compares to ensure written == read */
> > >               for ( /* initted above */; x < (4096/sizeof(int)); x++ )
> > >               {
> > >                       if ( ((int *)to)[x] != ((int *)from)[x] ) {
> > >                               panic("fast_page_copy: dest value @ 0x%lx (%x) does not equal source value @ %lx (%x)!\n",
> > >                                               (long) to, ((int *)to)[x], (long) from, ((int *) from)[x] );
> > >                       }
> > >               }
> > >       }
> > -----------------------------------------------------cut here
> >
> >   Wouldn't it be correct to say that because it is panicking, the
> > page copy was not completed properly?
> 
> No, you are comparing the following two pages... from and to are
> incremented as the copy proceeds.  Subtract PAGE_SIZE from them before
> comparing.
> 
> --
> 
>                                 Brian Gerst