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Re: [PATCH] xen/arm: Fix compilation error when early printk is enabled

Hi Jan,

On 21/01/2021 10:24, Jan Beulich wrote:
On 21.01.2021 10:56, Julien Grall wrote:
Hi Jan,

On 21/01/2021 09:43, Jan Beulich wrote:
On 21.01.2021 10:30, Michal Orzel wrote:
Fix compilation error when enabling early printk, introduced
by commit aa4b9d1ee6538b5cbe218d4d3fcdf9548130a063:
debug.S: Assembler messages:
debug.S:31: Error: constant expression expected at operand 2 -- `ldr 
debug.S:38: Error: constant expression expected at operand 2 -- `ldr 

The fix is to include header <xen/page-size.h> which now contains
definitions for page/size/mask etc.

Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>

I'm sorry for the breakage, but I wonder how I should have noticed
the issue. In all the Arm .config-s I'm routinely building I can't
even see ...

--- a/xen/include/asm-arm/early_printk.h
+++ b/xen/include/asm-arm/early_printk.h
@@ -10,6 +10,7 @@
   #ifndef __ARM_EARLY_PRINTK_H__
   #define __ARM_EARLY_PRINTK_H__
+#include <xen/page-size.h> #ifdef CONFIG_EARLY_PRINTK

... a respective Kconfig setting, i.e. it's not like I simply
failed to enable it.

EARLY_PRINTK is defined in arch/arm/Kconfig.debug and is selected when
you specify the UART to use.

Assuming you are only build testing, you could add the following for


Ah yes, this works, thanks. The "optional" on the choice isn't
very helpful I suppose, because when going from an existing
.config one would neither find a setting presently turned off
in that .config, nor will there be a prompt.

Do you have a suggestion how the "choice" can appear in the .config?

I suppose any page-aligned base address is fine to use for my
build-testing-only purposes?

The base address doesn't need to be page-aligned (some HW have multiple UARTs in the same 4K region).


Julien Grall



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