Re: [PATCH v2] ARM: map ATAGs when not in first 1MB of RAM

Russell,

On 01/28/2011 08:10 AM, Russell King - ARM Linux wrote:

On Fri, Jan 28, 2011 at 08:00:46AM -0600, Rob Herring wrote:

quoted

@@ -206,11 +206,17 @@ __create_page_tables:
  #endif

  	/*
-	 * Then map first 1MB of ram in case it contains our boot params.
+	 * Then map boot params address in r2 or
+	 * the first 1MB of ram if boot params address is not specified.
  	 */
-	add	r0, r4, #PAGE_OFFSET>>  18
-	orr	r6, r7, r8
-	str	r6, [r0]
+	mov	r0, r2, lsr #20
+	movs	r0, r0, lsl #20
+	moveq	r0, r8
+	sub	r3, r0, r8
+	add	r3, r3, #PAGE_OFFSET
+	add	r3, r4, r3, lsr #18
+	orr	r6, r7, r0
+	str	r6, [r3]

Wouldn't:
	str	r6, [r4, r3, lsr #18]
work here?

Not on Thumb2:

arch/arm/kernel/head.S:218: Error: Thumb supports only LSL in shifted 
register indexing -- `str r6,[r4,r3,lsr#18]'

Rob

* Rob Herring [off-list ref] [110128 07:10]:

Russell,

On 01/28/2011 08:10 AM, Russell King - ARM Linux wrote:

quoted

On Fri, Jan 28, 2011 at 08:00:46AM -0600, Rob Herring wrote:

quoted

@@ -206,11 +206,17 @@ __create_page_tables:
 #endif

 	/*
-	 * Then map first 1MB of ram in case it contains our boot params.
+	 * Then map boot params address in r2 or
+	 * the first 1MB of ram if boot params address is not specified.
 	 */
-	add	r0, r4, #PAGE_OFFSET>>  18
-	orr	r6, r7, r8
-	str	r6, [r0]
+	mov	r0, r2, lsr #20
+	movs	r0, r0, lsl #20
+	moveq	r0, r8
+	sub	r3, r0, r8
+	add	r3, r3, #PAGE_OFFSET
+	add	r3, r4, r3, lsr #18
+	orr	r6, r7, r0
+	str	r6, [r3]

Wouldn't:
str	r6, [r4, r3, lsr #18]
work here?

Not on Thumb2:

arch/arm/kernel/head.S:218: Error: Thumb supports only LSL in
shifted register indexing -- `str r6,[r4,r3,lsr#18]'

Acked-by: Tony Lindgren <tony@atomide.com>