Date: Thu, 1 May 2008 10:18:11 +0200 From: Roman Divacky <rdivacky@freebsd.org> To: Pieter de Boer <pieter@thedarkside.nl> Cc: freebsd-emulation@freebsd.org Subject: Re: Linux compat ioctl return values Message-ID: <20080501081811.GB54624@freebsd.org> In-Reply-To: <481897AB.7070003@thedarkside.nl> References: <481897AB.7070003@thedarkside.nl>
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On Wed, Apr 30, 2008 at 06:00:43PM +0200, Pieter de Boer wrote: > Hi, > > I've been working on a kernel driver that creates a device. This device > in turn is opened and ioctl'd from a Linux executable. I've registered a > handler for these ioctl's and my ioctl handler is succesfully executed. > > My ioctl-handler returns a large positive value, but the userland > application retrieves the value 1, EPERM. If I return 42, the userland > application retrieves 42, but 260 is retrieved as 1. It appears there's a > threshold somewhere above which the return value is set to 1, but I > haven't been able to find out where in the code this is done. The Linux > executable actually expects the value I return, and doesn't work when > EPERM is found instead. > > So, the question is: does anyone know where such a threshold may > reside and how to work around it? this is done in (for i386) sys/i386/i386/trap.c around line 1050. in short, we define in the sysvec structure sv_errtbl and if returned error > the size of the table we just return -1. error table for linux is roughly to 70. thats why you are getting -1 (1 after translation) you might extend the errno table (i386/linux/linux_sysvec.c for i386, line 126) if you provide (tested!) patch for i386/amd64, I am sure it will get commited roman
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