Re: [Xen-devel] [PATCH] xen/x86: Be more power-efficient when waiting forever

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.12.13 at 15:38, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> There is one final for(;;); loop, but is in common code and immediately
> following a call to panic(), so is actually dead code and will be cleaned up
> in v2 of my "noreturn" series at the start of 4.5

In the context of this, this one ...

> --- a/xen/arch/x86/efi/boot.c
> +++ b/xen/arch/x86/efi/boot.c
> @@ -201,7 +201,8 @@ static void __init __attribute__((__noreturn__)) 
> blexit(const CHAR16 *str)
>          efi_bs->FreePages(xsm.addr, PFN_UP(xsm.size));
>  
>      efi_bs->Exit(efi_ih, EFI_SUCCESS, 0, NULL);
> -    for( ; ; ); /* not reached */
> +    for ( ; ; ) /* not reached */
> +        halt();

... seems pointless (but of course also not wrong).

> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -1448,7 +1448,8 @@ void __init do_early_page_fault(struct cpu_user_regs 
> *regs)
>          printk("Stack dump: ");
>          while ( ((long)stk & ((PAGE_SIZE - 1) & ~(BYTES_PER_LONG - 1))) != 0 
> )
>              printk("%p ", _p(*stk++));
> -        for ( ; ; ) ;
> +        for ( ; ; )
> +            halt();

While clearly this one is desirable.

Jan


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