Re: [RFC/BUG?] ide_cs's removable status

[Alan Cox]

On Mer, 2005-09-21 at 17:15 +0100, Richard Purdie wrote:
> As ide_cs only creates the block devices when a card is present, I think
> it shouldn't be set as removable. As a point of reference, the MMC
> system does not set the removable flag for exactly this reason (There is
> an email from Russell King explaining this -
> http://lkml.org/lkml/2005/1/8/165).

I can't comment on the MMC layer or its core requirements as I don't
know them well. IDE PCMCIA does however encompass removal devices. The
removable flag is set so that we get removable media behaviour - that is
the media can change under us and we must not cache partition data. The
current behavioiur in that sense is correct.

> 
> It is worth noting the MMC subsystem works with my evil udev script. If
> I apply the patch below (which removes the removable flag for flash
> devices), I don't see this loop.

But does MMC have a media change detect, and if not does the right thing
occur if you swap cards with partition tables ?

> 1. Can anyone provide details on what the bits in id->config really
> mean?  

ATA standards are all available for download.

> 2. Which other drivers exploit the "if (id->config & (1<<7))
> drive->removable = 1;" code? Is it just ide_cs?

It might be currently because the old IDE layer has no hotplug support
(not even for PCMCIA - it happens to work some days) but that wasn't
true in 2.4-ac or some 2.6-ac.

It sounds like something needs to be smarter about whether the media has
changed - could be kernel but it seems like a user space problem. I note
that the standard Gnome tools "just work" in this case so perhaps you
can see how they do it.

Alan

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