Re: [Minios-devel] [UNIKRAFT PATCH] plat: Configure stack size page order

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey Costin,

Thanks a lot for this patch. I am currently having a look but need some 
clarifications.
1) Why did you expose the option int the platform submenu? It is 
obviously changing something in architecture headers?
2) Did you check the interrupt stack for Xen on x86? It seems that this 
one is just sized to PAGE_SIZE. I think this can get critical for thread 
current retrieval, right? See: plat/xen/x86/arch_events.c and
plat/xen/x86/traps.c .
Do you by chance remember why we have the boot stack twice as big?
See: xen/x86/setup.c

3) More as a note: Xen on Arm32 seems not to follow any STACK_SIZE 
definition at all. We should probably put a note on this somewhere. I am 
not sure if it is worth fixing it - who knows what we are going to do 
with this architecture-platform-combination. I rather expect that we are 
going towards Arm64 for Xen in the future.
Thanks,

Simon

On 27.08.19 09:56, Costin Lupu wrote:
> This patch adds a config option for configuring the stack size page order. We
> need this for supporting large stacks.
>
> Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
> ---
>   arch/arm/arm/include/uk/asm/limits.h    | 2 +-
>   arch/arm/arm64/include/uk/asm/limits.h  | 2 +-
>   arch/x86/x86_64/include/uk/asm/limits.h | 2 +-
>   plat/Config.uk                          | 9 +++++++++
>   4 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm/arm/include/uk/asm/limits.h 
> b/arch/arm/arm/include/uk/asm/limits.h
> index 085761c3..e2298d6b 100644
> --- a/arch/arm/arm/include/uk/asm/limits.h
> +++ b/arch/arm/arm/include/uk/asm/limits.h
> @@ -39,7 +39,7 @@
>   #define __PAGE_MASK           (~((__PAGE_SIZE) - 1))
>   #endif
>   
> -#define __STACK_SIZE_PAGE_ORDER	2
> +#define __STACK_SIZE_PAGE_ORDER        CONFIG_STACK_SIZE_PAGE_ORDER
>   #define __STACK_SIZE          (__PAGE_SIZE * (1 << __STACK_SIZE_PAGE_ORDER))
>   
>   #define __WORDSIZE		32
> diff --git a/arch/arm/arm64/include/uk/asm/limits.h 
> b/arch/arm/arm64/include/uk/asm/limits.h
> index cec05641..fb70f2ba 100644
> --- a/arch/arm/arm64/include/uk/asm/limits.h
> +++ b/arch/arm/arm64/include/uk/asm/limits.h
> @@ -40,7 +40,7 @@
>   #define __PAGE_MASK           (~((__PAGE_SIZE) - 1))
>   #endif
>   
> -#define __STACK_SIZE_PAGE_ORDER	4
> +#define __STACK_SIZE_PAGE_ORDER        CONFIG_STACK_SIZE_PAGE_ORDER
>   #define __STACK_SIZE  (__PAGE_SIZE * (1 << __STACK_SIZE_PAGE_ORDER))
>   #define __STACK_ALIGN_SIZE    16
>   
> diff --git a/arch/x86/x86_64/include/uk/asm/limits.h b/arch/x86/x86_64/include/uk/asm/limits.h
> index a969bd17..21814044 100644
> --- a/arch/x86/x86_64/include/uk/asm/limits.h
> +++ b/arch/x86/x86_64/include/uk/asm/limits.h
> @@ -39,7 +39,7 @@
>   #define __PAGE_MASK           (~((__PAGE_SIZE) - 1))
>   #endif
>   
> -#define __STACK_SIZE_PAGE_ORDER	4
> +#define __STACK_SIZE_PAGE_ORDER        CONFIG_STACK_SIZE_PAGE_ORDER
>   #define __STACK_SIZE          (__PAGE_SIZE * (1 << __STACK_SIZE_PAGE_ORDER))
>   
>   #define __WORDSIZE		64
> diff --git a/plat/Config.uk b/plat/Config.uk
> index 8a878eb0..d0b99bd5 100644
> --- a/plat/Config.uk
> +++ b/plat/Config.uk
> @@ -25,3 +25,12 @@ config HZ
>         help
>                 Configure the timer interrupt frequency.
>                 Only change this if you know what you're doing.
> +
> +config STACK_SIZE_PAGE_ORDER
> +       int
> +       prompt "Stack size page order"
> +       default 4
> +       help
> +               Indirectly configures the stack size by changing the stack size 
> page
> +               order. Stack size is equal with 2^order * page size (e.g. 4KB).
> +               Only change this if you know what you're doing.
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