Re: PCI NVRAM Memory Card

[Johannes Erdfelt <johannes@erdfelt.com>]

On Fri, Aug 10, 2001, Eric W. Biederman <ebiederm@xmission.com> wrote:
> Johannes Erdfelt <johannes@erdfelt.com> writes:
> 
> > On Fri, Aug 10, 2001, Eric W. Biederman <ebiederm@xmission.com> wrote:
> > > Mike Jadon <mikej@umem.com> writes:
> > > 
> > > > My company has released a PCI NVRAM memory card but we haven't developed a
> > Linux
> > 
> > > > 
> > > > driver for it yet.  We want the driver to be open to developers to build
> > upon.
> > 
> > > > Is there a specific path we should follow with this being our goal?  
> > > 
> > > You might want to check out the development of the mtd subsystem.
> > > http://www.linux-mtd.infradead.org/
> > > 
> > > This is probably what you want to write a driver for for your NVRAM PCI card.
> > 
> > Not really.
> > 
> > In their case, it's a bunch of standard SDRAM on a PCI card with a
> > battery backup. It's not flash.
> > 
> > A block device is all that's needed.
> 
> O.k. that make sense, NVRAM has so many meanings...  It still might
> make sense to support things like JFFS, and friends, though.  So the
> reference isn't totally wasted.  

As a block device, anything is available to be used :)

> Somehow I missed the reference to a description of what kind of
> hardware is being discussed.  I wonder if the card can do DMA.
> Without bus mastering it looks tricky to get burts over the PCI bus,
> which would intern mean the card would be relatively slow.  And for
> things like keeping a journal for your filesystem generally the faster
> the better.  Being able to get 128MB/s would be pretty cool.

It can do DMA, even scatter gather. It's 64 bit too. It's pretty nice.

JE