Re: [linux-usb-devel] Re: hotplugging to deal with firmware download

[Brad Hards <bhards@bigpond.net.au>]

On Sun, 2 Jun 2002 15:50, Oliver Neukum wrote:
> Am Sonntag, 2. Juni 2002 13:11 schrieb Brad Hards:
> > On Mon, 3 Jun 2002 00:44, Oliver Neukum wrote:
> > > Am Sonntag, 2. Juni 2002 01:16 schrieben Sie:
> > > > On Sun, 2 Jun 2002 02:07, Oliver Neukum wrote:
> > > > > The problem is that this cannot simply work, because a filesystem
> > > > > may be mounted by nfs.
> > > >
> > > > How is this a problem? You simply need to bring the driver up before
> > > > you remount the nfs filesystem. If you assume that your firmware is
> > > > on that filesystem, then you couldn't have mounted it in the first
> > > > place.
> > > >
> > > > What am I missing here?
> > >
> > > Paging. As soon as user space is running, dirty pages may be written
> > > out And in order to run a user space firmware loader, user space must
> > > be functional, or am I overlooking something?
> >
> > The software support option requires swap to store to, right? That had
> > better be on a local disk, or it doesn't matter whether the firmware is
> > in userspace or not. Realistically, swap over a network block device
> > isn't a problem worth trying to solve.
>
> Not only swap, but any file opened for writing may be written to
> if you allocate memory.
If a file is opened for writing, it doesn't matter whether you allocate memory 
or not, it still may be written to. Sync, journalling, that process dirtying 
more pages, whatever.

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