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From: "Nikita V. Youshchenko" <yoush@cs.msu.su>
To: LKML <linux-kernel@vger.kernel.org>
Subject: Extended error reporting to user space?
Date: Tue, 16 Feb 2010 15:20:26 +0300
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Hi

I'm developing a device driver that, in it's ioctl()s, accepts a complex 
data structure. Before doing it's operation, it performs large number of 
checks if data is valid. If one of those checks fail, driver 
returns -EINVAL.

Unfortunately this -EINVAL is not really useful. E.g. if a developer, 
sitting in his IDE and debugging his code, will see ioctl() 
returning -EINVAL, and will have hard times finding what exactly is wrong.

Before inventing driver-specific extended error reporting, I'd like to ask 
if there is anything more or less generic for this.
I believe situation when -Exxx is too weak interface for error reporting is 
common.

Nikita