Hi David,
On Mon, Feb 27, 2023 at 6:01 PM David Hildenbrand <david@xxxxxxxxxx> wrote:
/*
* Externally used page protection values.
diff --git a/arch/microblaze/include/asm/pgtable.h b/arch/microblaze/include/asm/pgtable.h
index 42f5988e998b..7e3de54bf426 100644
--- a/arch/microblaze/include/asm/pgtable.h
+++ b/arch/microblaze/include/asm/pgtable.h
* - All other bits of the PTE are loaded into TLBLO without
* * modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for
* software PTE bits. We actually use bits 21, 24, 25, and
@@ -155,6 +155,9 @@ extern pte_t *va_to_pte(unsigned long address);
#define _PAGE_ACCESSED 0x400 /* software: R: page referenced */
#define _PMD_PRESENT PAGE_MASK
+/* We borrow bit 24 to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE _PAGE_DIRTY
_PAGE_DIRTY is 0x80, so this is also bit 7, thus the new comment is
wrong?
In the example, I use MSB-0 bit numbering (which I determined to be
correct in microblaze context eventually, but I got confused a couple a
times because it's very inconsistent). That should be MSB-0 bit 24.
Thanks, TIL microblaze uses IBM bit numbering...
I assume IBM bit numbering corresponds to MSB-0 bit numbering, correct?
Correct, as seen in s370 and PowerPC manuals...
I recall that I used the comment above "/* Definitions for MicroBlaze.
*/" as an orientation.
0 1 2 3 4 ... 18 19 20 21 22 23 24 25 26 27 28 29 30 31
RPN..................... 0 0 EX WR ZSEL....... W I M G
Indeed, that's where I noticed the "unconventional" numbering...
So ... either we adjust both or we leave it as is. (again, depends on
what the right thing to to is -- which I don't know :) )
It depends whether you want to match the hardware documentation,
or the Linux BIT() macro and friends...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
