> On 6 Dec 2021, at 17:05, Julien Grall <[email protected]> wrote:
>
> 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
>
Hi Julien,
> Can you provide some information on the setup? Is it using UEFI?
Yes it is a platform with 32gb of ram, I’ve built Xen with ACPI support and
it’s starting using UEFI+ACPI.
>
>> 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.
The code that it’s failing is this, inside efi_process_memory_map_bootinfo(…)
in the arch/arm/efi/efi-boot.h:
#ifdef CONFIG_ACPI
else if ( desc_ptr->Type == EfiACPIReclaimMemory )
{
if ( !meminfo_add_bank(&bootinfo.acpi, desc_ptr) )
{
PrintStr(L"Error: All " __stringify(NR_MEM_BANKS)
" acpi meminfo mem banks exhausted.\r\n");
return EFI_LOAD_ERROR;
}
}
#endif
>
>> 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.
I can do that.
Cheers,
Luca
>
>> +
>> 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
