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Re: [PATCH 2/2] xen/arm32: head: Improve logging in head.S



On 02/11/2023 10:23, Michal Orzel wrote:
          /* Address in the runtime mapping to jump to after the MMU is enabled 
*/
          mov_w lr, primary_switched
@@ -593,6 +603,21 @@ enable_mmu:
          mcr   CP32(r0, HSCTLR)       /* now paging is enabled */
          isb                          /* Now, flush the icache */

+        /*
+         * At this stage, the UART address will depend on whether the
+         * temporary mapping was created or not.
+         *
+         * If it was, then the UART will be mapped in the temporary
+         * area. Otherwise, it will be mapped at runtime virtual
+         * mapping.
+         */
+#ifdef CONFIG_EARLY_PRINTK
+        teq   r12, #1               /* Was the temporary mapping created? */
+        mov_w_on_cond eq, r11, TEMPORARY_EARLY_UART_VIRTUAL_ADDRESS
Shouldn't the clobber list be updated?

I missed this comment. I understand it will get clobbered today, but thinking a bit more, I would actually prefer if r11 is updated to EARLY_UART_ADDRESS just right after calling switch_to_runtime_mapping.

So we can add more prints in remove_identity_mapping() and remove_temporary_mapping().

I will have a look to update this patch.

Cheers,

--
Julien Grall



 


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