USB file mmap

Jeshwanth Kumar N K jeshkumar555 at gmail.com
Mon Jul 7 15:56:26 EDT 2014


Hi Greg,

Thanks for the reply.

I recently purchased an mbed board
https://mbed.org/platforms/mbed-LPC1768/ (friend recommended) to learn
USB Mass storage class. And used OpenLPC usb stack with fatfs example
to check how it works (used protocol analyser and stuff, to know whats
happening). In that they are reading each buffer, i mean copying
buffer (8k) of data to RAM and process it. And other idea I found is
using diskio function in openLPC stack to read the data in USB flash
(but this is without file system).

As a Linux user I knew in Linux we can do mmap easily for a file (with
filesystem). So thought of asking from where to start understanding
these concepts :).

Greg is it OK to ask this question here?

Thanks
On 07-Jul-2014 10:00 pm, "Greg KH" <greg at kroah.com> wrote:

> On Mon, Jul 07, 2014 at 07:30:07PM +0530, Jeshwanth Kumar N K wrote:
> > Hello List,
> > I am trying to understand mmap on files residing in USB flash, so can you
> > please give a pointer from where I can start to understand this? I mean
> how it
> > works, and which part in kernel takes care of it.
>
> That's a _huge_ stack you are talking about here involving a vfs, the
> memory management core, a filesystem, block layer, SCSI, and USB, at the
> very least.
>
> What _exactly_ are you looking to understand here?  And where in the
> code have you looked and need help with?  What documents have you read
> that were unclear?  And why do you need this information?
>
> greg k-h
>
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