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SubjectRe: [PATCH 1/2] firewire: firewire is a big-endian bus
On Apr 21 Laurent Vivier wrote:
> So, dump config_rom data as big-endian values.
>
> The value given by /sys/bus/firewire/devices/fw0 were correctly
> given on a big-endian host (like powermac) not on a little-endian host
> (like PC), for instance:
>
> 00000000 87 a4 04 04 34 39 33 31 22 a2 00 f0 33 22 11 00 |....4931"...3"..|
> 00000010 66 66 66 33 0b dd 05 00 c0 83 00 0c 1e 0d d0 03 |fff3............|
> 00000020 03 00 00 81 01 00 00 17 08 00 00 81 b7 4c 06 00 |.............L..|
> 00000030 00 00 00 00 00 00 00 00 75 6e 69 4c 69 46 20 78 |........uniLiF x|
> 00000040 69 77 65 72 00 00 65 72 1c ff 03 00 00 00 00 00 |iwer..er........|
> 00000050 00 00 00 00 75 6a 75 4a |....ujuJ|
> 00000058
>
> instead of:
>
> 00000000 04 04 a4 87 31 33 39 34 f0 00 a2 22 00 11 22 33 |....1394...".."3|
> 00000010 33 66 66 66 00 05 dd 0b 0c 00 83 c0 03 d0 0d 1e |3fff............|
> 00000020 81 00 00 03 17 00 00 01 81 00 00 08 00 06 4c b7 |..............L.|
> 00000030 00 00 00 00 00 00 00 00 4c 69 6e 75 78 20 46 69 |........Linux Fi|
> 00000040 72 65 77 69 72 65 00 00 00 03 ff 1c 00 00 00 00 |rewire..........|
> 00000050 00 00 00 00 4a 75 6a 75 |....Juju|
> 00000058
>
> This patch corrects this.
>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>

As defined in Documentation/ABI/stable/sysfs-bus-firewire we deliberately
export the Configuration ROM as an array of host-endian quadlets. As a
stable kernel ABI, this will not be changed.

(A python script called crpp which transforms this kind of binary data into
a richly annotated hexdump is available as part of the jujuutils package,
or standalone from http://me.in-berlin.de/~s5r6/linux1394/utils/.)

> ---
> drivers/firewire/core-device.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
> index f9e3aee..5245567 100644
> --- a/drivers/firewire/core-device.c
> +++ b/drivers/firewire/core-device.c
> @@ -399,14 +399,14 @@ static ssize_t config_rom_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> struct fw_device *device = fw_device(dev);
> - size_t length;
> + size_t i;
>
> down_read(&fw_device_rwsem);
> - length = device->config_rom_length * 4;
> - memcpy(buf, device->config_rom, length);
> + for (i = 0; i < device->config_rom_length; i++)
> + ((u32 *)buf)[i] = be32_to_cpu(device->config_rom[i]);
> up_read(&fw_device_rwsem);
>
> - return length;
> + return i * 4;
> }
>
> static ssize_t guid_show(struct device *dev,



--
Stefan Richter
-=====-===== -=-- =-=-=
http://arcgraph.de/sr/


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