On Thu, Jun 27, 2013 at 02:58:34PM -0500, Scott Wood wrote: > On 06/26/2013 09:00:33 PM, Kevin Hao wrote: > >This is based on the codes in the head_44x.S. Since we always align to > >256M before mapping the PAGE_OFFSET for a relocatable kernel, we also > >change the init tlb map to 256M size. > > Why 256M?
For two reasons:
1. This is the size which both e500v1 and e500v2 support.
2. Since we always use the PAGE_OFFSET as 0xc0000000, the 256M is
max alignment value we can use for this virtual address.
>
> This tightens the alignment requirement for dynamic memstart.
Yes. But since RELOCATABLE is a superset of DYNAMIC_MEMSTART, we can always
use RELOCATABLE instead of DYNAMIC_MEMSTART for fsl booke board in any cases.
So DYNAMIC_MEMSTART will seem not so useful after we enable this feature.
> And
> what about boards with less than 256 MiB of RAM?
It should be fine. We just create the map in the tlb. The MM still use
the real size of memory.
>
> >@@ -176,6 +176,8 @@ skpinv: addi r6,r6,1 /*
> >Increment */
> > /* 7. Jump to KERNELBASE mapping */
> > lis r6,(KERNELBASE & ~0xfff)@h
> > ori r6,r6,(KERNELBASE & ~0xfff)@l
> >+ rlwinm r7,r25,0,4,31
> >+ add r6,r7,r6
>
> Please consider using the more readable form of rlwinm/rlwimi:
>
> rlwinm r7,r25,0,0x0fffffff
Sure.
>
> > #elif defined(ENTRY_MAPPING_KEXEC_SETUP)
> > /*
> >diff --git a/arch/powerpc/kernel/head_fsl_booke.S
> >b/arch/powerpc/kernel/head_fsl_booke.S
> >index d10a7ca..c3b4c8e53 100644
> >--- a/arch/powerpc/kernel/head_fsl_booke.S
> >+++ b/arch/powerpc/kernel/head_fsl_booke.S
> >@@ -83,10 +83,43 @@ _ENTRY(_start);
> > andc r31,r20,r18 /* r31 = page base */
> > or r31,r31,r19 /* r31 = devtree phys addr */
> > mfspr r30,SPRN_MAS7
> >-
> >- li r25,0 /* phys kernel start (low) */
> > li r24,0 /* CPU number */
> >- li r23,0 /* phys kernel start (high) */
> >+
> >+#ifdef CONFIG_RELOCATABLE
> >+ bl 0f /* Get our runtime address */
> >+0: mflr r3 /* Make it accessible */
> >+ addis r3,r3,(_stext - 0b)@ha
> >+ addi r3,r3,(_stext - 0b)@l /* Get our current runtime base */
> >+
> >+ /* Translate _stext address to physical, save in r23/r25 */
> >+ tlbsx 0,r3 /* must succeed */
> >+
> >+ mfspr r16,SPRN_MAS1
> >+ mfspr r20,SPRN_MAS3
> >+ rlwinm r17,r16,25,0x1f /* r17 = log2(page size) */
> >+ li r18,1024
> >+ slw r18,r18,r17 /* r18 = page size */
> >+ addi r18,r18,-1
> >+ and r19,r3,r18 /* r19 = page offset */
> >+ andc r25,r20,r18 /* r25 = page base */
> >+ or r25,r25,r19 /* r25 = _stext phys addr */
> >+ mfspr r23,SPRN_MAS7
>
> This duplicates the code for finding the device tree physical
> address... maybe factor it out into a function?
Sure.
>
> >@@ -197,7 +230,58 @@ _ENTRY(__early_start)
> >
> > bl early_init
> >
> >-#ifdef CONFIG_DYNAMIC_MEMSTART
> >+#ifdef CONFIG_RELOCATABLE
> >+ /*
> >+ * Relocatable kernel support based on processing of dynamic
> >+ * relocation entries.
> >+ *
> >+ * r25/r23 will contain RPN/ERPN for the start address of memory
>
> The start of memory or the start of the kernel?
Should be the start of the kernel. Will fix the comment.
>
> >+ */
> >+ lis r3,kernstart_addr@ha
> >+ la r3,kernstart_addr@l(r3)
> >+
> >+#ifdef CONFIG_PHYS_64BIT
> >+ stw r23,0(r3)
> >+ stw r25,4(r3)
> >+#else
> >+ stw r25,0(r3)
> >+#endif
>
> This part looks the same for relocatable and dynamic memstart -- can
> you avoid duplicating?
OK.
>
> >+ /*
> >+ * Compute the virt_phys_offset :
> >+ * virt_phys_offset = stext.run - kernstart_addr
> >+ *
> >+ * stext.run = (KERNELBASE & ~0xfffffff) + (kernstart_addr &
> >0xfffffff)
> >+ * When we relocate, we have :
> >+ *
> >+ * (kernstart_addr & 0xfffffff) = (stext.run & 0xfffffff)
> >+ *
> >+ * hence:
> >+ * virt_phys_offset = (KERNELBASE & ~0xfffffff) -
> >+ * (kernstart_addr & ~0xfffffff)
> >+ *
> >+ */
> >+
> >+ /* KERNELBASE&~0xfffffff => (r4,r5) */
>
> >+ li r4, 0 /* higer 32bit */
> >+ lis r5,KERNELBASE@h
>
> Please be consistent with whitespace.
Fixed.
Thanks,
Kevin
>
> -Scott
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