Re: [Xen-devel] [PATCH RFC 5/7] xen: arm: rewrite start of day page table and cpu bring up

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Thu, 2013-09-19 at 12:36 +0100, Tim Deegan wrote:
> 
> > +        mov   r3, #0x0
> > +        lsr   r2, r8, #21
> > +        lsl   r2, r2, #21            /* r2: 2MB-aligned paddr of DTB */
> > +        orr   r2, r2, #PT_UPPER(MEM)
> > +        orr   r2, r2, #PT_LOWER(MEM) /* r2:r3 := 2MB RAM incl. DTB */
> > +        ldr   r4, =BOOT_MISC_VIRT_START
> > +        mov   r4, r4, lsr #18        /* Slot for BOOT_MISC_VIRT_START */
> > +        strd  r2, r3, [r1, r4]       /* Map it in the early boot slot */
> > +        dsb   sy
> 
> Do we need any TLB flushes here, since we're modifying the live
> pagetables?  I don't recall whether the ARM MMU is guaranteed not to
> cache/prefetch negative results (like the x86 one is). 

My recollection is that it doesn't.

Ian.


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