Hi Jan,

On 09/08/2024 10:34, Jan Beulich wrote:
On 08.08.2024 17:50, Ayan Kumar Halder wrote:
On 08/08/2024 13:49, Jan Beulich wrote:
On 08.08.2024 14:09, Ayan Kumar Halder wrote:
@@ -58,9 +58,13 @@ config PADDR_BITS
        default 40 if ARM_PA_BITS_40
        default 48 if ARM_64
+config HAS_VMAP
+       def_bool y
With this being always enabled, ...
I had to define the config somewhere. It seemed this is the correct
place to define as HAS_VMAP will be turned off when MPU is introduced.

So, it will be

config HAS_VMAP

             def_bool n

At that time, only MMU will select HAS_VMAP.
Well, but why is it not simply

config HAS_VMAP
        bool

from the very beginning? (There should never be "def_bool n" imo, btw.)

--- a/xen/include/xen/vmap.h
+++ b/xen/include/xen/vmap.h
@@ -141,7 +141,9 @@ void *arch_vmap_virt_end(void);
   /* Initialises the VMAP_DEFAULT virtual range */
   static inline void vm_init(void)
   {
+#ifdef CONFIG_MMU
       vm_init_type(VMAP_DEFAULT, (void *)VMAP_VIRT_START, 
arch_vmap_virt_end());
+#endif
   }
What about non-Arm, which all have MMUs but no corresponding Kconfig
setting?
AFAICS , the only file that is of our concern xen/common/vmap.c It is
enclosed with VMAP_VIRT_START which is defined in mmu specific file
(xen/arch/arm/include/asm/mmu/layout.h).

So, it will not be compiled for Arm MPU arch.
Yet that wasn't my question. I asked about non-Arm, for all of which it
looks like you're changing behavior of vm_init() (by suddenly making it
do nothing).

Oh now I see what you mean. There is no CONFIG_MMU is x86 , yet it is used to enclose a common code which is a mistake.

So, we should introduce HAS_VMAP in xen/common/Kconfig and select it from X86, X86_64 and Arm.

Is my understanding correct ?

- Ayan



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