| Message ID | 1461160464-2194-1-git-send-email-van.freenix@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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.freenix@gmail.com> > Cc: Stefano Stabellini <sstabellini@kernel.org> > Cc: Julien Grall <julien.grall@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,
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 */ /* ... map of vaddr(start) in boot_third */ mov x1, xzr
The 'Base address for 4K mapping' is '(x19 >> THIRD_SHIFT) << THIRD_SHIFT'. Also we are building 4K page mapping, not section mapping. Signed-off-by: Peng Fan <van.freenix@gmail.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Julien Grall <julien.grall@arm.com> --- xen/arch/arm/arm64/head.S | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)