Re: POSIX.Memory_Mapping.Map_Memory

["Adrian Hoe" <byhoe@greenlime.com>]

Mark Lorenzen wrote:
> "Adrian Hoe" <byhoe@greenlime.com> writes:
>
> > Hi,
> >
> > I am working on video_device with Video_4_Linux based on the work
of
> > Anders Gidenstam. According to latest V4L documentation, capturing
with
> > Read has been deprecated and the only method now is by the use of
mmap.
>

>>>> snip <<<<


> > Device.Fd := Open (To_POSIX_String (File_Name),
> > Read_Only);
>
> You open the device in read-only.
>
> [cut]
>
> >
> > -- Permission Denied exception was raised here at the line below!!!
> > Map := Map_Memory (System.Storage_Elements.Storage_Offset
> > (Buf_Size),
> > POSIX.Memory_Mapping.Allow_Read +
> > POSIX.Memory_Mapping.Allow_Write,
> > POSIX.Memory_Mapping.Map_Shared,
> > Device.Fd,
> > 0);
>
> But you try to map it in read/write mode.

I open with Read_Write option and raised POSIX.POSIX_ERROR :
INVALID_ARGUMENT at the same line.

> Maybe thats the case of the exception. Do you have to be root in
order
> to open the device at all?


No, I don't have to be root to open the device. Some applications are
able to open it and the camera and video card work.



--
Adrian Hoe