Hi all.
I have similar problem.
Currently applications on linux can't use mmap of framebuffer(/dev/fb0).
When apps access memory to get through mmap, it occurs page fault.
Without goos, fbdrv of L4 cell, mag, l4fb drv in linux, etc on,
Is there ways that it modify <linux lcd device driver> little bit as other
linux device drivers
In other words, could Apps use allocated memory in linux kernel?
As a guide,
Because of using dedicated frame buffer only in one cell(linux), it mustn't
use things like goos, mag.
thanks
------------------------------
Message: 1
Date: Tue, 24 Jan 2012 20:03:36 +0100
From: Adam Lackorzynski adam@os.inf.tu-dresden.de
To: l4-hackers@os.inf.tu-dresden.de
Subject: Re: Fiasco.OC x86 IO port permission bitmap
Message-ID: 20120124190336.GE2897@os.inf.tu-dresden.de
Content-Type: text/plain; charset=iso-8859-1
Hi,
On Mon Jan 23, 2012 at 15:54:29 -0800, Daniel Waddington wrote:
I want to use the TSS I/O permission bit map to support fine grained
control of I/O access for user-level apps (x86 32 bit target). From
looking at the kernel code, I believe the bit map is switched out
per-process as part of the Context class (Space::_io_space) -
correct me if I am wrong. My query is how to set/clear the bits for
a given target task from a "root" task with sufficient privileges
(e.g., base caps and sigma0 caps). I could extend the kernel
scheduler protocol, but I don't want to do this if there is already
a clean way in place.
IO-ports are handled similar to page-faults, i.e. they can be mapped to
other tasks, and the pager receives io-page-faults when one of its
clients accesses an IO-port without having it. For example look for
L4_PROTO_IO_PAGE_FAULT and l4_iofpage().
Adam
--
Adam adam@os.inf.tu-dresden.de
Lackorzynski
http://os.inf.tu-dresden.de/~adam/
------------------------------
Message: 2
Date: Tue, 24 Jan 2012 13:12:03 -0800
From: Daniel Waddington
d.waddington@samsung.com
To: Adam Lackorzynski
adam@os.inf.tu-dresden.de
Cc: l4-hackers@os.inf.tu-dresden.de
Subject: Re: Fiasco.OC x86 IO port permission bitmap
Message-ID:
4F1F1EA3.7060309@samsung.com
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Hi Adam,
I see. So it seems that you have to map all of the IO port space before
getting IOPL raised to 3 (assuming Kconfig IO_PROT & !IO_PROT_3) and
therefore the default mode of operation is a driver will map the whole
space if it wants to use IO instructions directly. Is it right that you
currently don't use the TSS IO bitmap to allow access to only specific
IO ports with CPL > IOPL?
Thanks
Daniel
On 01/24/2012 11:03 AM, Adam Lackorzynski wrote:
> Hi,
>
> On Mon Jan 23, 2012 at 15:54:29 -0800, Daniel Waddington wrote:
>> I want to use the TSS I/O permission bit map to support fine grained
>> control of I/O access for user-level apps (x86 32 bit target). From
>> looking at the kernel code, I believe the bit map is switched out
>> per-process as part of the Context class (Space::_io_space) -
>> correct me if I am wrong. My query is how to set/clear the bits for
>> a given target task from a "root" task with sufficient privileges
>> (e.g., base caps and sigma0 caps). I could extend the kernel
>> scheduler protocol, but I don't want to do this if there is already
>> a clean way in place.
> IO-ports are handled similar to page-faults, i.e. they can be mapped to
> other tasks, and the pager receives io-page-faults when one of its
> clients accesses an IO-port without having it. For example look for
> L4_PROTO_IO_PAGE_FAULT and l4_iofpage().
>
>
> Adam