RE: [PATCH 15/77] Staging: hv: blkvsc: Add the appropriateMODULE_ALIAS() line

[KY Srinivasan]

> -----Original Message-----
> From: Greg KH [mailto:greg@xxxxxxxxx]
> Sent: Tuesday, July 05, 2011 11:42 PM
> To: KY Srinivasan
> Cc: gregkh@xxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxx; Haiyang Zhang; Hank
> Janssen
> Subject: Re: [PATCH 15/77] Staging: hv: blkvsc: Add the appropriate
> MODULE_ALIAS() line
> 
> On Wed, Jul 06, 2011 at 12:40:42AM +0000, KY Srinivasan wrote:
> > > > diff --git a/drivers/staging/hv/blkvsc_drv.c
> b/drivers/staging/hv/blkvsc_drv.c
> > > > index 5842db8..9496abe 100644
> > > > --- a/drivers/staging/hv/blkvsc_drv.c
> > > > +++ b/drivers/staging/hv/blkvsc_drv.c
> > > > @@ -1027,5 +1027,6 @@ static void __exit blkvsc_exit(void)
> > > >  MODULE_LICENSE("GPL");
> > > >  MODULE_VERSION(HV_DRV_VERSION);
> > > >  MODULE_DESCRIPTION("Microsoft Hyper-V virtual block driver");
> > > > +MODULE_ALIAS("vmbus:hv_block");
> > >
> > > No, these should be automagically generated with the MODULE_DEVICE_ID()
> > > macro that you use in the module with the GUID there, instead of this.
> >
> > I think you mean MODULE_DEVICE_TABLE()?
> 
> Yes, sorry for the typo.
> 
> > I actually went down that path first
> > adding code  to  file2alias.c for parsing the vmbus ID table. Given that this
> approach
> > would make it  impossible to support auto-loading of these drivers
> > on many of the released kernels,
> 
> Wait, what?  What is a "released kernel"?  We are working on the
> in-kernel patch, we don't care about older distros/releases for this
> work at all.  Also, it doesn't make sense at all, why would the change I
> asked for make any difference on older distros/kernels?

I understand we don't care here about older kernels and I will do what you
have suggested. I just wanted to give you the rationale for choices I made:
We are currently supporting older distros/kernels using these upstream bits.
With the MODULE_ALIAS() approach, since I did not have to change any code
outside the hv directory, this was possible. I was mostly concerned about 
having to make changes to code outside the hv directory and figuring out 
how to build and propagate these changes (file2alias.c) in older kernels. 


> 
> > I chose to go with the MODULE_ALIAS() macro that did not need any
> > changes outside our drivers. In both methods, the formatting of the
> > name is bus specific since I would be writing the code to parse the
> > table in file2alias.c.
> 
> Yes, that is what is needed to be done.
> 
> > Granted, I have been quite unimaginative in my alias names, but I
> > thought they were reasonably descriptive. If at all possible, for the
> > reasons listed above, I would prefer to use the MODULE_ALIAS() macro
> > (I could embed all or part of the guid in the alias). Let me know.
> 
> Please do the correct thing and use MODULE_DEVICE_TABLE().

We have four drivers now excluding vmbus and soon we will have only three
drivers with the merge of block and stor drivers. Would you still recommend I use the
full guid to name these drivers. Rather than embedding the entire 128bit guid in module
aliases, I was thinking of setting up a more reasonable namespace for these drivers
(like what virtio has done for instance). Let me know if this is ok with you if I took that
route (mapping the guid to small integers and having these integers be used in alias strings).

Regards,

K. Y  

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