Hi Marc,
endianess is handled by lower level functions (see for ex pcan_usb_fd_get_user_devid()/pcan_usb_fd_set_user_devid() in PATCH 2/6).
This data is really a number and must be treated as such. The "ethtool -e" interface only displays a silly memory dump not very practical to read a number (especially a 32-bit one), requiring the use of hexdump such as:
ethtool -e can1 raw on | hexdump -v -e '1 "%u\n"'
to have a usable display. Unfortunately, these formats do not take endianess into account (AFAIK). Maybe you know another way?
Regards,
— Stéphane
De: Marc Kleine-Budde
Envoyé: Lundi 31 janvier 2022 15:31
À: Stéphane Grosjean
Cc: linux-can Mailing List
Objet: Re: [PATCH 6/6] can: peak_usb: add ethtool interface to user defined flashed device number
On 31.01.2022 14:25:28, Stéphane Grosjean wrote:
> >> + u32 devid;
> >>
> >> + memcpy(data, (u8 *)&devid + eeprom->offset, eeprom->len);
> >
> > cast not needed.
> >
>
> We need to cast the u32 * into a u8 * because eeprom->offset is a count of bytes, isn't it?
Doh! right.
What about endianness? I think it's better to use an array of bytes
everywhere.
Marc
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