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Subject: Re: Starting APs earlier during boot
To: John Baldwin <jhb@freebsd.org>, arch@freebsd.org
References: <1730061.8Ii36ORVKt@ralph.baldwin.cx>
From: Julian Elischer <julian@freebsd.org>
Message-ID: <56C4061B.6010601@freebsd.org>
Date: Tue, 16 Feb 2016 21:33:15 -0800
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On 16/02/2016 12:50 PM, John Baldwin wrote:
> Currently the kernel bootstraps the non-boot processors fairly early in the
> SI_SUB_CPU SYSINIT.  The APs then spin waiting to be "released".  We currently
> release the APs as one of the last steps at SI_SUB_SMP.  On the one hand this
> removes much of the need for synchronization while SYSINITs are running since
> SYSINITs basically assume they are single-threaded.  However, it also enforces
> some odd quirks.  Several places that deal with per-CPU resources have to
> split initialization up so that the BSP init happens in one SYSINIT and the
> initialization of the APs happens in a second SYSINIT at SI_SUB_SMP.
>
> Another issue that is becoming more prominent on x86 (and probably will also
[...]

what is the goal?  cleaner  code? faster boot?
>