linux-kernel - Re: [PATCH 10/12] ACPI: processor: refactor internal map_lsapic

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Message-ID: <20100125224628.GB2828@grease.ALLEYCAT>
Date:	Mon, 25 Jan 2010 15:46:28 -0700
From:	Alex Chiang <achiang@...com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/12] ACPI: processor: refactor internal
	map_lsapic_id()

Hi David,

* David Rientjes <rientjes@...gle.com>:
> On Mon, 25 Jan 2010, Alex Chiang wrote:
> 
> > diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
> > index 9213f95..ec5989c 100644
> > --- a/drivers/acpi/processor_core.c
> > +++ b/drivers/acpi/processor_core.c
> > @@ -83,27 +83,17 @@ static int map_lsapic_id(struct acpi_subtable_header *entry,
> >  {
> >  	struct acpi_madt_local_sapic *lsapic =
> >  		(struct acpi_madt_local_sapic *)entry;
> > -	u32 tmp = (lsapic->id << 8) | lsapic->eid;
> >  
> > -	/* Only check enabled APICs*/
> >  	if (!(lsapic->lapic_flags & ACPI_MADT_ENABLED))
> >  		return 0;
> >  
> > -	/* Device statement declaration type */
> >  	if (device_declaration) {
> > -		if (entry->length < 16)
> > -			printk(KERN_ERR PREFIX
> > -			    "Invalid LSAPIC with Device type processor (SAPIC ID %#x)\n",
> > -			    tmp);
> 
> Why drop this error message?

It didn't seem to add any value.

If BIOS declares a processor with the Device statement in ACPI
and it has an invalid length, there's nothing that a user can do
about it.

Arguably, the message might be useful during internal platform
bringup (or new firmware validation), but even that's a hard sell
to me, since one of the first things a bringup engineer would
notice would be missing CPUs, and it wouldn't take that long to
realize that firmware was broken; why make upstream carry around
extra baggage for internal firmware debugging?

But I don't have a strong opinion here. If folks think that
message is useful, I can respin leaving it in.

Thanks,
/ac

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