From: Mark Lorenzen <mark.lorenzen@ofir.dk>
Subject: Re: POSIX.Memory_Mapping.Map_Memory
Date: 29 Jan 2005 17:20:27 +0100
Date: 2005-01-29T17:20:27+01:00 [thread overview]
Message-ID: <m3k6pwky0k.fsf@0x50a5b1db.boanxx18.adsl-dhcp.tele.dk> (raw)
In-Reply-To: 1107014307.952357.216870@f14g2000cwb.googlegroups.com
"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.
>
> I open a device and read the device with the following procedures, Open
> and Map_Image as below. In Procedure Map_Image, I make a call to
> Map_Memory (POSIX.Memory_Mapping) and raise an exception:
>
> POSIX.POSIX_ERROR : PERMISSION_DENIED
>
> -----------------------------------------------------------------------
[cut]
> 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.
Maybe thats the case of the exception. Do you have to be root in order
to open the device at all?
[cut]
> Adrian Hoe
- Mark Lorenzen
next prev parent reply other threads:[~2005-01-29 16:20 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-29 15:58 POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-01-29 16:20 ` Mark Lorenzen [this message]
2005-01-29 16:31 ` POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-01-29 18:44 ` POSIX.Memory_Mapping.Map_Memory Mark Lorenzen
2005-01-30 2:45 ` POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-01-30 2:48 ` POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-01-30 15:39 ` POSIX.Memory_Mapping.Map_Memory Mark Lorenzen
2005-01-30 16:02 ` POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-01-30 16:19 ` POSIX.Memory_Mapping.Map_Memory Mark Lorenzen
2005-01-30 16:36 ` POSIX.Memory_Mapping.Map_Memory Mark Lorenzen
2005-01-30 18:51 ` POSIX.Memory_Mapping.Map_Memory Florian Weimer
2005-02-27 6:59 ` POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-02-27 13:03 ` POSIX.Memory_Mapping.Map_Memory Mark Lorenzen
2005-01-30 16:05 ` POSIX.Memory_Mapping.Map_Memory Adrian Hoe
2005-01-30 16:22 ` POSIX.Memory_Mapping.Map_Memory Mark Lorenzen
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