From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Date: Wed, 16 Jun 2004 20:22:06 +0000 Subject: Re: [PATCH] early console registration Message-Id: <200406161422.06366.bjorn.helgaas@hp.com> List-Id: References: <200405141425.59867.jbarnes@engr.sgi.com> In-Reply-To: <200405141425.59867.jbarnes@engr.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Tuesday 15 June 2004 7:12 am, Jesse Barnes wrote: > Yeah, that's fine. In fact, I've tested something similar and sent it to > Andrew, but he came back and asked why not just set CPU 0 online early? And > given that CPU 0 is 'online' as soon as the kernel starts executing head.S, > it seems like it *should* keep working, and we should probably keep it that > way. It's *not* online as soon as it starts head.S, though -- that's what I meant about preserving the original cpu_online semantics. It currently means that at least cpu_init() has been called, so memory allocation, per-cpu data, and interrupts should work. If we mark CPU 0 as 'online' earlier, some hypothetical new code could test cpu_online(0) and incorrectly assume per-cpu data works. But AFAIK, there is no such code now, and I don't have any better ideas, so maybe we should just go with your ia64-specific patch for now.