Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932376Ab0FOTyy (ORCPT ); Tue, 15 Jun 2010 15:54:54 -0400 Received: from lirone.symas.net ([64.71.152.235]:58816 "EHLO lirone.symas.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757835Ab0FOTyx (ORCPT ); Tue, 15 Jun 2010 15:54:53 -0400 Message-ID: <4C17DA85.40803@symas.com> Date: Tue, 15 Jun 2010 12:54:45 -0700 From: Howard Chu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; rv:1.9.3a5pre) Gecko/20100607 Firefox 3.6 MIME-Version: 1.0 To: Alan Cox CC: linux-kernel@vger.kernel.org, Greg KH Subject: Re: [PATCH] tty: Add EXTPROC support for LINEMODE References: <20100615202924.24446d28@lxorguk.ukuu.org.uk> In-Reply-To: <20100615202924.24446d28@lxorguk.ukuu.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3071 Lines: 83 Alan Cox wrote: >> bit set, and the data will be the contents of a struct termios. >> This allows the process on the server side of the pty to know >> when the state of the terminal has changed, and what the new >> state is. > > First problem - the kernel and user idea of struct termios don't match. OK, since you mention it again down below I'll respond to this last. >> diff --git a/arch/alpha/include/asm/termbits.h b/arch/alpha/include/asm/termbits.h >> index ad854a4..879dd35 100644 >> --- a/arch/alpha/include/asm/termbits.h >> +++ b/arch/alpha/include/asm/termbits.h >> @@ -180,6 +180,7 @@ struct ktermios { >> #define FLUSHO 0x00800000 >> #define PENDIN 0x20000000 >> #define IEXTEN 0x00000400 >> +#define EXTPROC 0x10000000 > > For Alpha this value should match OSF if possible. I'm grubbing around looking for a live Alpha system now, doesn't seem likely that I'll find one. Not sure what needs to match here, it's also unlikely that OSF/1 (or any other SVR4 platform) ever provided a definition for this bit. Looking at the telnet README: >>>> This is a distribution of both client and server telnet. These programs have been compiled on: telnet telnetd BSD 4.4 x x BSD 4.3 Reno X X UNICOS 8.0 X X UNICOS 7.C X X UNICOS 7.0 X X UNICOS 6.1 X X BSDI 1.0 X X Solaris 2.2 x x (no linemode in server) Solaris 2.3 x x (no linemode in server) SunOs 4.1.3 X X (no linemode in server) Ultrix 4.3 X X (no linemode in server) DYNIX V3.0.17.9 X X (no linemode in server) HP-UX 8.0 x x (no linemode in server) <<<< I doubt that anyone ever ported this feature over to those OSes. > > >> + if (cs& TIOCPKT_IOCTL) { >> + c = sizeof(struct termios); >> + if (c> nr) >> + c = nr; >> + copy_to_user(b, tty->link->termios, c); >> + nr -= c; >> + b += c; >> + } > > This is where the wheels come off the bus. > > The kernel use struct ktermios which is what tty->link->termios is > > The C library presents this via struct termios which is a glibc invention > dependant on the C library and which is converted by libc from struct > termios or struct termios2 depending on your C library > > How you fix that given a broken by design historic Unix interface which > pastes arbitary struct termios objects into the data stream is an > interesting question - doubly so when like most Unixen we have also have > extended terminal attributes as well (termiox) Are you suggesting that this is completely unfixable/unworkable? Would it be sufficient to use kernel_termios_to_user_termios() ? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/