linux-kernel - Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu

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Date:	Wed, 12 Dec 2007 15:21:32 +0100
From:	Andi Kleen <ak@...e.de>
To:	Neil Horman <nhorman@...driver.com>
Cc:	Yinghai Lu <yhlu.kernel@...il.com>,
	Ben Woodard <woodard@...hat.com>,
	Neil Horman <nhorman@...hat.com>, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...e.de>,
	hbabu@...ibm.com, Andi Kleen <andi@...stfloor.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com
Subject: Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on
	boot cpu

> +	htcfg = read_pci_config(num, slot, func, 0x68);
> +	if (htcfg & (1 << 18)) {	
> +		printk(KERN_INFO "Detected use of extended apic ids on hypertransport bus\n");
> +		if ((htcfg & (1 << 17)) == 0) {
> +			printk(KERN_INFO "Enabling hypertransport extended apic interrupt broadcast\n");
> +			printk(KERN_INFO "Note this is a bios bug, please contact your hw vendor\n");

I'm not convinced the message is correct. e.g. on a system with only a dual core not enabling
that is fine, but the extended IDs might be still set.

>  #endif /* CONFIG_ACPI */
>  
> -static void __init nvidia_bugs(void)
> +static void __init nvidia_bugs(int num, int slot, int func)
>  {
> +	static int fix_applied = 0;
> +
> +	if (fix_applied++)
> +		return;

This looks like the wrong place to do this. Better add a flag or something
in the structure. Dito others.

Also while not a problem here in general it's bad style to add potential
wrapping bugs like this. Never use ++ for flags.

-Andi
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