On 21/04/16 02:06, Peng Fan wrote:
Hi Julien,
Hello Peng,
On Wed, Apr 20, 2016 at 03:44:09PM +0100, Julien Grall wrote:
Hello Peng,
On 20/04/16 14:54, Peng Fan wrote:
Use shift operator, but not muliplication.
No function change.
Why? The compiler will calculate the address at compilation time.
Yeah. The compiler will do this. I just think in asm, we rarely use
multiplication. In this file, there is "cmp x1, #(LPAE_ENTRIES<<3)",
here use shift operator but not multiplication.
It took me a bit of time to understand that 8 is the number of byte of
an LPAE entries. IMHO the "<< 3" would be more confusing.
So I would introduce a macro to get the slot based of an index.
Something like:
LPAE_SLOT(slot) ((slot) * 8)
And add a comment to explain why 8. You could even introduce
LPAE_ENTRY_SIZE.
Regards,
Thanks,
Peng.
Regards,
Signed-off-by: Peng Fan <van.free...@gmail.com>
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Julien Grall <julien.gr...@arm.com>
---
xen/arch/arm/arm64/head.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 05e3db0..ad6e593 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -524,7 +524,7 @@ paging:
lsl x2, x2, #THIRD_SHIFT /* 4K aligned paddr of UART */
mov x3, #PT_DEV_L3
orr x2, x2, x3 /* x2 := 4K dev map including UART */
- str x2, [x1, #(FIXMAP_CONSOLE*8)] /* Map it in the first fixmap's
slot */
+ str x2, [x1, #(FIXMAP_CONSOLE << 3)] /* Map it in the first fixmap's
slot */
1:
/* Map fixmap into boot_second */
--
Julien Grall
--
Julien Grall
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