lkml.org 
[lkml]   [2009]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: Vramfs: filesystem driver to utilize extra RAM on VGA devices
    From
    Date
    On Mon, 2009-01-26 at 15:50 -0800, Jonathan Campbell wrote:
    > vramfs is designed to take the memory range and directly turn it into a
    > usable filesystem.
    > The structures are not actually in VRAM, but the file contents are.
    > Vramfs has a builtin mechanism as described to avoid conflicting with
    > the region in use by the framebuffer console.
    >
    > I don't really know about the mtd device, but I thought it would be good
    > kernel coding practice to write a filesystem driver to pull off a stunt
    > like that.
    >
    > I also wrote this in consideration of the GPU which probably wouldn't
    > know how to handle the fragmentation that would inevitably happen if
    > ext3 needed to write blocks in a non-contiguous manner, this fs enforces
    > the rule that files are always unbroken with only a start and length.
    >

    How do you accomplish that?

    (I haven't yet looked at your code...)

    -PWM


    > Also, doesn't mtd come in as a block device?
    > So you'd have to format the memory region using a filesystem like ext3,
    > right?
    > And as a block device you can't use mmap() to map that region directly
    > into your process space, right?
    > > Jonathan Campbell wrote:
    > >>
    > >> So far I've tested it against 2.6.25.17 and 2.6.28 on both x86 and
    > >> x86_64 with reads, writes, directory creation, symlink creation, and
    > >> mmap() and it seems to work fine.
    > >> Just give it a range of memory on the bus, or the
    > >> domain:bus:device:function numbers of a VGA PCI device, and it will
    > >> mount the VGA video RAM and allow files to exist there.
    > >> As a special hack: you can also specify the size of the active
    > >> framebuffer console so that fbcon doesn't collide with this driver
    > >> (unless you want to see what your files look like splattered across
    > >> your screen, ha). The active VRAM area becomes a "sentinel" file
    > >> named "framebuffer".
    > >>
    > >> What do you guys think?
    > >>
    > >
    > > How is this different from the MTD driver we already have?
    > >
    > > -hpa
    > > --
    > > To unsubscribe from this list: send the line "unsubscribe
    > > linux-kernel" in
    > > the body of a message to majordomo@vger.kernel.org
    > > More majordomo info at http://vger.kernel.org/majordomo-info.html
    > > Please read the FAQ at http://www.tux.org/lkml/
    > >
    > >
    >
    > _______________________________________________
    > devel mailing list
    > devel@linuxdriverproject.org
    > http://driverdev.linuxdriverproject.org/mailman/listinfo/devel



    \
     
     \ /
      Last update: 2009-01-29 18:07    [W:0.052 / U:31.516 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site