Date: Tue, 14 Aug 2018 20:45:26 -0400 From: Rich Felker <dalias@...c.org> To: Alexander Revin <lyssdod@...il.com> Cc: musl@...ts.openwall.com Subject: Re: Re: musl on a different syscall layer? On Tue, Aug 14, 2018 at 01:12:56AM +0200, Alexander Revin wrote: > > On Wed, Sep 17, 2014 at 7:02 PM, <u-wsnj@...ey.se> wrote: > >> On Wed, Sep 17, 2014 at 01:53:46PM -0400, Rich Felker wrote: > >>> The main requirement is having equivalent functionality available. On > >>> the BSD targets I've asked BSD folks about, there's supposedly no > >>> equivalent of futex except inthe Linux compat layer, which is pretty > >>> much a show-stopper unless/until it can be remedied. clone is a big > >>> unknown to me too. The other big potential problem is if the native > >>> syscall API requires a stack to communicate with the kernel (one or > >>> more BSDs require this, IIRC), since at least __unmapself needs to be > >>> able to call SYS_munmap and SYS_exit without a stack. > >> > >> Oh I see. > >> > >> This means "not much to hope for" (pity but good to know). > > > I don't think NetBSD uses the stack for syscalls on any common > > architecture, maybe on some of the obscure ones, but maybe you don't > > want to support them. > > > > Adding futex support to NetBSD would be an interesting project; it is > > not in the compat layer at present either, so that is a good reason to > > add it. NetBSD is pretty friendly... > > > > Justin (justin@...bsd.org) > > Hi guys, sorry for reviving a dead thread, but do you know if things > has changed ever since? I'm asking also because it would be nice to > unify efforts of porting musl to another archs - for example, openrisc > or m68k - though there're ports for both Linux and NetBSD, libc > support is kind of scattered over large codebase. I'm not aware of anything more on the NetBSD side. Note that "syscalls using stack" is no longer a show-stopper for musl. There's a portable, albeit less efficient, version of __unmapself that switches to a shared stack protected by a lock (with the magic exit futex automatically unlocking it atomically with thread termination). But this depends on that compat functionality or equivalent. Rich
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