Re: [Xen-devel] [PATCH v2 1/3] xen/x86: split boot trampoline into permanent and temporary part

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.03.17 at 07:25, <jgross@xxxxxxxx> wrote:
> @@ -131,6 +151,14 @@ start64:
>          movabs  $__high_start,%rax
>          jmpq    *%rax
>  
> +#include "wakeup.S"
> +
> +/* The first page of trampoline is permanent, the rest boot-time only. */
> +        .equ    trampoline_boot_start, trampoline_start + PAGE_SIZE
> +        .global trampoline_boot_start

The name is at least ambiguous - boot only code starts right here,
not at the next page boundary. Would it not work to use wakeup_stack
here, ...

> --- a/xen/arch/x86/boot/wakeup.S
> +++ b/xen/arch/x86/boot/wakeup.S
> @@ -1,6 +1,7 @@
>          .code16
>  
>  #define wakesym(sym) (sym - wakeup_start)
> +#define wakeup_stack trampoline_start + PAGE_SIZE

... omit this #define, and ...

> --- a/xen/arch/x86/xen.lds.S
> +++ b/xen/arch/x86/xen.lds.S
> @@ -335,3 +335,5 @@ ASSERT(IS_ALIGNED(__bss_end,        8), "__bss_end 
> misaligned")
>  
>  ASSERT((trampoline_end - trampoline_start) < TRAMPOLINE_SPACE - 
> MBI_SPACE_MIN,
>      "not enough room for trampoline and mbi data")
> +ASSERT((trampoline_boot_start - wakeup_stack_start) >= WAKEUP_STACK_MIN,
> +    "wakeup stack too small")

... use wakeup_stack here too?

Jan


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