Hi Luca,
On 06/12/2021 15:37, Luca Fancellu wrote:
Currently the maximum number of memory banks is fixed to
128, but on some new platforms that have a large amount
of memory, this value is not enough
Can you provide some information on the setup? Is it using UEFI?
and prevents Xen
from booting.
AFAIK, the restriction should only prevent Xen to use all the memory. If
that's not the case, then this should be fixed.
Create a Kconfig parameter to set the value, by default
128.
I think Xen should be able to boot on any platform with the default
configuration. So the value should at least be bumped.
Signed-off-by: Luca Fancellu <[email protected]>
---
xen/arch/arm/Kconfig | 8 ++++++++
xen/include/asm-arm/setup.h | 2 +-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index ecfa6822e4d3..805e3c417e89 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -25,6 +25,14 @@ menu "Architecture Features"
source "arch/Kconfig"
+config MEM_BANKS
+ int "Maximum number of memory banks."
+ default "128"
+ help
+ Controls the build-time size memory bank array.
+ It is the upper bound of the number of logical entities describing
+ the memory.
NR_MEM_BANKS is going to be used by multiple internal structure in Xen
(e.g. static memory, reserved memory, normal memory). So how could an
admin decide the correct value?
In particular for UEFI, we are at the mercy of the firmware that can
expose any kind of memory map (that's why we had to increase the
original number of banks).
So maybe it is time for us to move out from a static array and re-think
how we discover the memory.
That this is probably going to take some time to get it properly, so
I would be OK with bumping the value + a config gated UNSUPPORTED.
+
config ACPI
bool "ACPI (Advanced Configuration and Power Interface) Support
(UNSUPPORTED)" if UNSUPPORTED
depends on ARM_64
diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h
index 95da0b7ab9cd..785a8fe81450 100644
--- a/xen/include/asm-arm/setup.h
+++ b/xen/include/asm-arm/setup.h
@@ -6,7 +6,7 @@
#define MIN_FDT_ALIGN 8
#define MAX_FDT_SIZE SZ_2M
-#define NR_MEM_BANKS 128
+#define NR_MEM_BANKS CONFIG_MEM_BANKS
#define MAX_MODULES 32 /* Current maximum useful modules */
Cheers,
--
Julien Grall
