linux-kernel - Re: Access MSR functions in userspace?

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Message-ID: <47AA5A3D.9070707@zytor.com>
Date:	Wed, 06 Feb 2008 17:09:17 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Hasan Rashid <hasan@...italpath.net>
CC:	"'Maxim Levitsky'" <maximlevitsky@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Access MSR functions in userspace?

Hasan Rashid wrote:
> I am using kernel 2.4.32. Inside msr.c it is trying to register cpu/msr as
> shown here.
> 
> int __init msr_init(void)
> {
>   if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
>     printk(KERN_ERR "msr: unable to get major %d for msr\n",
> 	   MSR_MAJOR);
>     return -EBUSY;
>   }
>   
>   return 0;
> }
> 
> I did use the MAKEDEV script with the tools but since the msr module isn't
> trying to register at any of those locations, they don't work. 

Nonsense.  All that matters is major:minor.

> There is only one processor on my board, I am going to register device under
> cpu/0/msr and see if that solves the issue.

It's irrelevant where it "registers" (on your kernel it only affects 
/proc/devices, nothing else, unless you're using devfs, in which case, 
well, don't.)  The MAKEDEV script with the tools creates the appropriate 
device entries.

	-hpa
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