From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/8658 Path: news.gmane.org!not-for-mail From: Denys Vlasenko Newsgroups: gmane.linux.lib.musl.general Subject: Re: Re: musl and kernel headers [was Re: system-images 1.4.2: od is broken; bzip2 is missing] Date: Tue, 13 Oct 2015 14:10:24 +0200 Message-ID: References: <5612925A.4070402@landley.net> <20151006014426.GL8645@brightrain.aerifal.cx> <20151008165808.GZ8645@brightrain.aerifal.cx> <20151009194641.GI8645@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1444738267 7363 80.91.229.3 (13 Oct 2015 12:11:07 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 13 Oct 2015 12:11:07 +0000 (UTC) Cc: Rob Landley , Aboriginal Linux , musl To: Rich Felker Original-X-From: musl-return-8670-gllmg-musl=m.gmane.org@lists.openwall.com Tue Oct 13 14:10:59 2015 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1ZlyPy-0008Tt-QJ for gllmg-musl@m.gmane.org; Tue, 13 Oct 2015 14:10:58 +0200 Original-Received: (qmail 1961 invoked by uid 550); 13 Oct 2015 12:10:56 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 1940 invoked from network); 13 Oct 2015 12:10:55 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=YdLGaCRsfcC9s0wRdvCw3kyM9v5Mk+DuVU5JEkCc1vY=; b=nw0LkQl3Mhs0BGZMqxKk0451fKaL8uaoqT8fUh42ETcHR4DgFaVqPgrGLrXpX/BOGI ikg2UrIvILPmqrC0VA9Z01mwq1qUN9gKf55V3eLYn2qLzmXUVQlTZZfHgTRlspRvpT6P v0LSJ7k/jGoMV24vmoHgjUpi2R1akGTDrV+B8BMzW51qeTxjljMbVFv4N6cxykGbYZtZ c/sH9aVTfArSudyhn/I6XI8qSmsUvO+9FTlmpCgfVApVKA0eICCrwjBscSS53xE3zMCi oo9N19W7kXq+0SxZRy4od+mrV2kyPOx1QNr/lLfe1w6n6XruaJH2aCfCkbb5hEa4k3eb 1z+w== X-Received: by 10.140.85.135 with SMTP id n7mr38359360qgd.53.1444738243872; Tue, 13 Oct 2015 05:10:43 -0700 (PDT) In-Reply-To: <20151009194641.GI8645@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:8658 Archived-At: On Fri, Oct 9, 2015 at 9:46 PM, Rich Felker wrote: >> Looking at kernel's libc-compat.h, it looks like you can get away >> with using __UAPI_DEF_foo's like this? >> >> >> #if defined(__UAPI_DEF_SOCKADDR_IN) && __UAPI_DEF_SOCKADDR_IN == 1 >> /* kernel already defined the struct, do nothing */ >> #else >> struct sockaddr_in { >> ... >> }; > > This would address the case where the kernel header is included first, > but it's not a case I or most of the musl community wants to support, > because there's no guarantee that the kernel's definitions of these > structures will actually be compatible with use elsewhere in the libc > headers, etc. If kernel's definition does not match yours, there is a much bigger problem than "includes do not compile": kernel and userspace definitions of these structs *must* match (modulo harmless things like different typedef names for field types). So in this case either kernel or libc would need to be fixed. > The other direction, suppressing kernel headers' definition of the > structs, is what we want to work, but they've restricted their logic > for that to only work when __GLIBC__ is defined. :( Yes, you will have to do by hand the thing which kernel automagically does for glibc - namely, define to 0: >> #undef __UAPI_DEF_SOCKADDR_IN >> /* tell kernel to not define the struct */ >> #define __UAPI_DEF_SOCKADDR_IN 0 >> #endif > We could do something like this but then we would need to keep up with > the list of all the __UAPI defines we need to suppress unwanted kernel > definitions. Looking at libc-compat.h, this list is at the moment only about 13 defines long: #define __UAPI_DEF_IN_ADDR 0 #define __UAPI_DEF_IN_IPPROTO 0 #define __UAPI_DEF_IN_PKTINFO 0 #define __UAPI_DEF_IP_MREQ 0 #define __UAPI_DEF_SOCKADDR_IN 0 #define __UAPI_DEF_IN_CLASS 0 #define __UAPI_DEF_IN6_ADDR 0 #define __UAPI_DEF_SOCKADDR_IN6 0 #define __UAPI_DEF_IPV6_MREQ 0 #define __UAPI_DEF_IPPROTO_V6 0 #define __UAPI_DEF_IPV6_OPTIONS 0 #define __UAPI_DEF_IN6_PKTINFO 0 #define __UAPI_DEF_IP6_MTUINFO 0 > What if we could get the kernel to change the #if defined(__GLIBC__) > to #if defined(__GLIBC__) || defined(__UAPI_DONTNEED_DEFS) or similar, > so that there would only be one macro we need to define, and the > kernel would then use the same logic it uses with glibc to suppress > all of these. Or ask kernel to remove "define to 0" glibc hack and ask glibc to do its own job. Why one libc should have preferential treatment? Or ask kernel to stop using structures with userspace names. This should not be that hard: struct __kernel_sockaddr_in {...} #if __KERNEL__ # define sockaddr_in __kernel_sockaddr_in #endif