input_event for 64-bit kernel and 32-bit userland.

input_event for 64-bit kernel and 32-bit userland.

[Pavel Kiryukhin]

Hi all,
I stuck in simple situation:
USB mouse (or keyboard). n64 kernel (2.4.20), n32 userland.

Userspace application tries to read "input_event" (16 bytes) from 
"/dev/input/event0" [ read(fd,&key_ev, sizeof(key_ev)) ],
input core driver treats "input_event" as 24 bytes structure. It is due 
to different size of  "timeval" (and finally  "long") in n64 kernel and 
n32 userland.

Application gets some garbage as mouse events . No solutions like "ioctl 
wrappers" applicable in this case.

I don't want to change any arch independent files, but can not find any
acceptable solution. It looks like headers "/usr/include/linux/input.h" 
in root file system and "/include/linux/input.h" in kernel should be the 
same,
 (All works fine as soon as I declare a new "input_event" structure in 
user application that corresponds in size to kernel
structure - but this is not acceptable).

Can anybody advice me what to do with the difference in "input_event"
structure sizes in o32/n32 userland and n64 kernel? Just a general 
approach that can be used when  driver's read/write operation treat some 
values as 64 bit while user application tries to read/write 32-bit 
values (based on the same headers).

Please, don't kick me if solution is simple and obvious.
---
Thanks,
Pavel Kiryukhin.

Re: input_event for 64-bit kernel and 32-bit userland.

[Jan-Benedict Glaw]

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On Wed, 2004-06-02 14:06:10 +0400, Pavel Kiryukhin <savl@dev.rtsoft.ru>
wrote in message <40BDA692.50606@dev.rtsoft.ru>:

> Userspace application tries to read "input_event" (16 bytes) from 
> "/dev/input/event0" [ read(fd,&key_ev, sizeof(key_ev)) ],
> input core driver treats "input_event" as 24 bytes structure. It is due 
> to different size of  "timeval" (and finally  "long") in n64 kernel and 
> n32 userland.

You'd probably Cc: that to LKML, too. That's an issue for all systems
running 64bit kernel with 32bit userland (eg. Ultra-Sparc, PPC64, IA64,
x86_64, ...).

MfG, JBG

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