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From: Paul Brook <paul@codesourcery.com>
Date: Thu, 16 Aug 2012 15:56:50 +0100
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Message-ID: <201208161556.52432.paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH 0/3] Drop default SD card creation
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Kevin Wolf <kwolf@redhat.com>, patches@linaro.org, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

> On 16 August 2012 15:11, Markus Armbruster <armbru@redhat.com> wrote:
> > Peter Maydell <peter.maydell@linaro.org> writes:
> >> As suggested in the recent discussion on Markus' patchset to suppress
> >> unused default drives, this patchset cleans up the omap and pxa2xx
> >> 
> >> SD card controllers to behave like the other controllers:
> >>  * the init function looks for the next IF_SD drive
> >>  * if there isn't one, we start up as a controller with no card
> >>  
> >>    present
> > 
> > Isn't this an incompatible change?  Before, you get an SD card reader
> > backed by an empty BDS default.  You can load/unload cards in the
> > monitor.  After, you get an SD card reader that isn't backed by a BDS by
> > default.  Device models prepared for that can treat it as permanently
> > empty.
> 
> Hmm, yes, but most of our SD controllers already act that way.
> We should probably fix them all...
> 
> So what's the block layer equivalent of drive_get_next() that always
> returns us something we can get a bdrv from?

I think this may be the wrong way to fix this.  SD cards aren't really have 
removable media.  In the same way that a SCSI HDD are generally not removable 
media - you hotplug the whole drive.

Don't we really want a proper QOM device for the SD card, with hotplug 
support.

Paul