> include/asm-i386/fixmap.h
>
>
> "Leave one empty page between vmalloc'ed areas and the start of the fixmap,
> and leave one page empty at the top of mem."
this reads like that's (only?) a problem for last page in
_virtual_ address space, isn't it ?
I'm looking for a method to map/read the last _physical_ page
(bus addresses, actually it's a graphics card's BIOS which got
mapped just below 4GB by main board's PCI BIOS configuration).
do these "compile-time 'special' virtual addresses" limitations
apply to bus addresses too ?
>
> I would guess that you can't map the fixmap, either.
>
>
> Nathan
>
>
> > -----Original Message-----
> > From: root [SMTP:koenig@tat.physik.uni-tuebingen.de]
> > Sent: Sunday, October 10, 1999 9:53 PM
> > To: linux-kernel-list
> > Cc: Egbert Eich
> > Subject: mmapping of page 0xfffff000 impossible ?
> >
> > why isn't it possible to mmap the very last page in 32bit address space ?
> >
> > strace output for 2.2.12 of the small sample program below:
> > open("/dev/mem", O_RDWR) = 3
> > mmap(NULL, 61440, PROT_READ, MAP_SHARED, 3, 0xffff0000) = 0x4011b000
> > mmap(NULL, 61441, PROT_READ, MAP_SHARED, 3, 0xffff0000) = -1 EINVAL
> > (Invalid argument)
> >
> > --------------------------------------------------------------------------
> > -----
> > #include <unistd.h>
> > #include <sys/mman.h>
> > #include <fcntl.h>
> > main()
> > {
> > int f;
> > void *p;
> >
> > f = open("/dev/mem", O_RDWR);
> >
> > /* this will work ... */
> > p = mmap(NULL, 0xf000, PROT_READ, MAP_SHARED, f, 0xffff0000);
> >
> > /* this one won't :-( */
> > p = mmap(NULL, 0xf001, PROT_READ, MAP_SHARED, f, 0xffff0000);
> > }
> > --------------------------------------------------------------------------
> > -----
> >
> >
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> > Please read the FAQ at http://www.tux.org/lkml/
Harald
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