Date: Thu, 9 Nov 2023 10:03:05 -0700 From: Warner Losh <imp@bsdimp.com> To: Doug Rabson <dfr@rabson.org> Cc: Zhenlei Huang <zlei@freebsd.org>, FreeBSD Current <current@freebsd.org>, Konstantin Belousov <kib@freebsd.org> Subject: Re: kldunload kernel: How should the kernel behave when it is requested to unload itself Message-ID: <CANCZdfqzDaYfJi6XzhvfpCxEKX1FwA1A2b_dtH-h=_GTwPM8nw@mail.gmail.com> In-Reply-To: <CACA0VUggUqxTQ%2BrNRmAE0TyZr%2BiUumBOhwAVQATQ5MseT9A6zQ@mail.gmail.com> References: <07168C68-9F81-443C-AFB6-24958BB01F9E@FreeBSD.org> <CACA0VUggUqxTQ%2BrNRmAE0TyZr%2BiUumBOhwAVQATQ5MseT9A6zQ@mail.gmail.com>
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--0000000000001d92cd0609bb2e26 Content-Type: text/plain; charset="UTF-8" Yea. Kexec is what you'd need to do to get a new kernel... and we don't support kexec... so I agree this is good.. Warner On Thu, Nov 9, 2023, 9:34 AM Doug Rabson <dfr@rabson.org> wrote: > I think your intuition is correct - it never makes sense to unload the > kernel (IMO). I approved the review. > > Doug. > > > On Thu, 9 Nov 2023 at 16:10, Zhenlei Huang <zlei@freebsd.org> wrote: > >> Hi, >> >> This is *NOT* joking. >> >> While working on https://reviews.freebsd.org/D42527 I realized the >> module kernel also has userrefs, that is to say, userland can request >> to unload kernel, aka `kldunload kernel`. >> >> This is interesting. Well no doubt that the loader can unload kernel. >> Then after the kernel is loaded and has been initialized (SYSINIT), how >> should it behave when it get an unload request? >> >> I'm proposing https://reviews.freebsd.org/D42530 to do not allow >> unloading >> the kernel. It is by intuition. >> >> What do you think ? >> >> >> Best regards, >> Zhenlei >> >> --0000000000001d92cd0609bb2e26 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"auto">Yea. Kexec is what you'd need=C2=A0to do to get a new= kernel... and we don't support kexec... so I agree this is good..<div = dir=3D"auto"><br></div><div dir=3D"auto">Warner</div></div><br><div class= =3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Thu, Nov 9, 2023,= 9:34 AM Doug Rabson <<a href=3D"mailto:dfr@rabson.org">dfr@rabson.org</= a>> wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 = 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">I th= ink your intuition is correct - it never makes sense to unload the kernel (= IMO). I approved the review.<div><br></div><div>Doug.</div><div><br></div><= /div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">O= n Thu, 9 Nov 2023 at 16:10, Zhenlei Huang <<a href=3D"mailto:zlei@freebs= d.org" target=3D"_blank" rel=3D"noreferrer">zlei@freebsd.org</a>> wrote:= <br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8= ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,= 204,204);padding-left:1ex">Hi,<br> <br> This is *NOT* joking.<br> <br> While working on <a href=3D"https://reviews.freebsd.org/D42527" rel=3D"nore= ferrer noreferrer" target=3D"_blank">https://reviews.freebsd.org/D42527</a>= I realized the<br> module kernel also has userrefs, that is to say, userland can request<br> to unload kernel, aka `kldunload kernel`.<br> <br> This is interesting. Well no doubt that the loader can unload kernel.<br> Then after the kernel is loaded and has been initialized (SYSINIT), how<br> should it behave when it get an unload request?<br> <br> I'm proposing <a href=3D"https://reviews.freebsd.org/D42530" rel=3D"nor= eferrer noreferrer" target=3D"_blank">https://reviews.freebsd.org/D42530</a= > to do not allow unloading<br> the kernel. It is by intuition.<br> <br> What do you think ?<br> <br> <br> Best regards,<br> Zhenlei<br> <br> </blockquote></div> </blockquote></div> --0000000000001d92cd0609bb2e26--
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