Date: Wed, 20 Apr 2022 09:54:49 -0400 From: Rich Felker <dalias@...c.org> To: Christian Brauner <brauner@...nel.org> Cc: 王洪亮 <wanghongliang@...ngson.cn>, musl@...ts.openwall.com Subject: Re: Re: add loongarch64 port On Wed, Apr 20, 2022 at 03:33:25PM +0200, Christian Brauner wrote: > On Wed, Apr 20, 2022 at 05:09:08PM +0800, 王洪亮 wrote: > > > > 在 2022/4/14 下午5:36, Christian Brauner 写道: > > > On Wed, Apr 13, 2022 at 10:09:31AM -0400, Rich Felker wrote: > > > > On Wed, Apr 13, 2022 at 03:25:05PM +0200, Arnd Bergmann wrote: > > > > > On Wed, Apr 13, 2022 at 11:04 AM Christian Brauner <brauner@...nel.org> wrote: > > > > > > On Wed, Apr 13, 2022 at 10:26:06AM +0200, Arnd Bergmann wrote: > > > > > > > The normal rule is that we don't define obsolete system calls in new > > > > > > > architectures when an improved variant has been added, e.g. oldoldstat, > > > > > > > oldstat, stat, newstat and stat64 have all been replaced by statx over > > > > > > > the decades. I was expecting the same to be true for clone(), but if > > > > > > > clone3() is not meant as a replacement, we can keep both around. > > > > > > No, I agree with you on this and would like to only implement clone3() > > > > > > on new architectures. > > > > > > > > > > > > What I'm asking is whether removing the size == 0 check is enough to > > > > > > unblock the missing behavior and whether you'd be on board with removing > > > > > > the check? > > > > > I think that's ok here, since we'd only rely on this for loongarch64 at the > > > > > moment. It would probably need to be documented in the man page > > > > > as a special case though. > > > > I'm okay with removing the check for size==0 (so size==0 will be > > > > allowed) and dropping __NR_clone on new archs, as long as it's noted > > > > in comments/documentation that size==0 is explicitly allowed so nobody > > > > breaks this in the future. > > > Ok, I'll try to have a patch ready early next week since I'm currently > > > out sick. > > > > Hi, > > > > I'm implementing __NR_clone3 syscall within __clone(). > > > > I have another problem:CLONE_DETACHED > > > > in musl,internal call __clone()(such as __pthread_create()),the input > > parameter flags > > > > has been set CLONE_DETACHED ,in kernel,there is a check in > > clone3_args_valid(), > > > > if the condition met,return false. > > > > How to deal with this problem? > > CLONE_DETACHED is meaningles since Linux on 2.6.2. There really should > be <=2.6.1 living kernel anywhere where CLONE_DETACHED does anything. > I've documented that in detail under  as: > > CLONE_DETACHED (historical) > For a while (during the Linux 2.5 development series) > there was a CLONE_DETACHED flag, which caused the parent > not to receive a signal when the child terminated. > Ultimately, the effect of this flag was subsumed under the > CLONE_THREAD flag and by the time Linux 2.6.0 was > released, this flag had no effect. Starting in Linux > 2.6.2, the need to give this flag together with > CLONE_THREAD disappeared. > > This flag is still defined, but it is usually ignored when > calling clone(). However, see the description of > CLONE_PIDFD for some exceptions. > > : https://man7.org/linux/man-pages/man2/clone.2.html > > Would it be possible to drop this flag from musl's pthread_create() > implementation? (Iirc, glibc dropped CLONE_DETACHED in 2004.) I think __clone should just mask it on newer archs. We support Linux 2.6.0 and if lack of CLONE_DETACHED causes bogus signals on 2.6.0 we should keep it. If it can be established that this doesn't happen and that CLONE_DETACHED just affected non-thread clones, we can probably safely drop it. Rich
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