Hello Peng, I would specific the file modified in the title.
On 20/04/16 14:54, Peng Fan wrote:
The 'Base address for 4K mapping' is '(x19 >> THIRD_SHIFT) << THIRD_SHIFT'.
The computation is a sequence of 2 instructions. I gave a look to the rest of the file and the comments are usually put on the first instruction.
So I would much prefer to stay consistent with the rest of the code.
Also we are building 4K page mapping, not section mapping.
To be fair, a page is a specialized section.
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 | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index 946e2c9..05e3db0 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -471,10 +471,10 @@ skip_bss: ldr x4, =boot_third add x4, x4, x20 /* x4 := paddr (boot_third) */ - lsr x2, x19, #THIRD_SHIFT /* Base address for 4K mapping */ - lsl x2, x2, #THIRD_SHIFT - mov x3, #PT_MEM_L3 /* x2 := Section map */ - orr x2, x2, x3 + lsr x2, x19, #THIRD_SHIFT + lsl x2, x2, #THIRD_SHIFT /* Base address for 4K mapping */ + mov x3, #PT_MEM_L3 + orr x2, x2, x3 /* x2 := Page map */
The section map is the combination of 2 instructions. With this change we don't know quickly what the purpose of "mov x3, #PT_MEM_L3".
/* ... map of vaddr(start) in boot_third */ mov x1, xzr
Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel