linux-kernel - Re: [PATCH 1/8] Add driver auto probing for x86 features v2

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Message-Id: <201112231416.09954.trenn@suse.de>
Date:	Fri, 23 Dec 2011 14:16:09 +0100
From:	Thomas Renninger <trenn@...e.de>
To:	Andi Kleen <andi@...stfloor.org>, Andi Kleen <ak@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, davej@...hat.com,
	kay.sievers@...y.org, axboe@...nel.dk, herbert@...dor.apana.org.au,
	ying.huang@...el.com, lenb@...nel.org, gregkh@...e.de
Subject: Re: [PATCH 1/8] Add driver auto probing for x86 features v2

Hi,

for info:

On Tuesday, December 20, 2011 12:46:27 AM Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> Old patchkit, resurrect due to popular demand.
...
> +	n = snprintf(buf, size, "x86cpu:vendor:%04x:family:%04x:model:%04x:feature:",
this must be uppercase hex values (%04X)
...
> +		if (boot_cpu_has(i)) {
> +			n = snprintf(buf, size, ",%04x", i);
same here.
Looks like a string compare is happening and in
scripts/mod/file2alias.c
sizeof(field) == 2 ? "%04X"
is used and the modalias added to the driver and showing up
in /lib/modules/*/modales.alias is uppercase.

...
> +	}
> +	*buf++ = ',';
> +	*buf++ = '\n';
this must be:
 +	*buf++ = '\0';
otherwise one can hit:
   WARNING: at lib/kobject_uevent.c:362 add_uevent_var+0xf2/0x100()
   add_uevent_var: buffer size too small
Hm, then /sys/devices/system/cpu/modalias has not a newline.
Using kzalloc in arch_cpu_uevent() should be the nicest way
to address this.

Now things work much better, hope that's all.
I just send out a new patchset (with cpuid vs cpu kobject broken out
in a separate patch for better backporting).

   Thomas
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