Re: [RFC PATCH 1/4] kconfig: allow configuration of maximum modules

["Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>]

On 5/31/22 05:25, Julien Grall wrote:
> Hi,
> 
> On 31/05/2022 03:41, Daniel P. Smith wrote:
>> diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig
>> index f16eb0df43..57b14e22c9 100644
>> --- a/xen/arch/Kconfig
>> +++ b/xen/arch/Kconfig
>> @@ -17,3 +17,15 @@ config NR_CPUS
>>         For CPU cores which support Simultaneous Multi-Threading or
>> similar
>>         technologies, this the number of logical threads which Xen will
>>         support.
>> +
>> +config NR_BOOTMODS
>> +    int "Maximum number of boot modules that a loader can pass"
>> +    range 1 64
> 
> OOI, any reason to limit the size?

I modelled this entirely after NR_CPUS, which applied a limit, and it
seemed reasonable to me at the time. I choose 64 since it was double
currently what Arm had set for MAX_MODULES. As such, I have no hard
reason for there to be a limit. It can easily be removed or adjusted to
whatever the reviewers feel would be appropriate.

>> +    default "8" if X86
>> +    default "32" if ARM
>> +    help
>> +      Controls the build-time size of various arrays allocated for
>> +      parsing the boot modules passed by a loader when starting Xen.
>> +
>> +      This is of particular interest when using Xen's hypervisor domain
>> +      capabilities such as dom0less.
>> diff --git a/xen/arch/arm/include/asm/setup.h
>> b/xen/arch/arm/include/asm/setup.h
>> index 2bb01ecfa8..312a3e4209 100644
>> --- a/xen/arch/arm/include/asm/setup.h
>> +++ b/xen/arch/arm/include/asm/setup.h
>> @@ -10,7 +10,8 @@
>>     #define NR_MEM_BANKS 256
>>   -#define MAX_MODULES 32 /* Current maximum useful modules */
>> +/* Current maximum useful modules */
>> +#define MAX_MODULES CONFIG_NR_BOOTMODS
> 
> There are only a handful number of use of MAX_MODULES in Arm. So I would
> prefer if we replace all the use with CONFIG_NR_BOOTMODS.

No problem, as I stated above, I mimicked what was done for NR_CPUS
which did a similar #define for MAX_CPUS.

v/r,
dps