From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adolf Belka To: development@lists.ipfire.org Subject: Re: Problem with trying to build qemu-9.0.2 - it requires dtc for all architectures Date: Wed, 04 Sep 2024 09:22:08 +0200 Message-ID: <433079f5-3b7d-404d-90d9-08b51900d044@ipfire.org> In-Reply-To: <23B802E6-CF76-4EFD-A5A5-29706580D401@ipfire.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6095632298780699970==" List-Id: --===============6095632298780699970== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hi Michael, On 04/09/2024 08:58, Michael Tremer wrote: > Hello, >=20 >> On 3 Sep 2024, at 21:06, Adolf Belka wrote: >> >> Hi All, >> >> On 03/09/2024 15:25, Adolf Belka wrote: >>> Hi Michael, >>> >>> On 03/09/2024 09:24, Michael Tremer wrote: >>>> Hello Adolf, >>>> >>>> Yes, you can make those changes. >>>> >>>> dtc is the device tree compiler and it should be quick to build. We just= didn=E2=80=99t do that since we didn=E2=80=99t have any use for it apart fro= m aarch64. >>>> >>>> Move it wherever you want. It should not have any further dependencies. = We can build it for all architectures. >>> >>> I did that and qemu found libfdt but then said that it was too old and th= at a min of 1.5.1 was required but the updated version of dtc I had built was= version 1.7.1 >>> >> I have found the section in meson.build where it checks for the fdt librar= y and it seems to me that the code says that if the system fdt is being used = then say that it is too old. I can't see any actual check of the version numb= er of libfdt. >=20 > Hmm, the code is not the cleanest, but it should perform a few checks befor= e it throws that error. The crucial part is here: >=20 >> if fdt.found() and cc.links(''=E2=80=99 >> ...''', >> dependencies: fdt) >> fdt_opt =3D 'system' >> elif fdt_opt =3D=3D 'system' >> error('system libfdt requested, but it is too old (1.5.1 or newer = required)') >> else >> fdt_opt =3D 'internal' >> fdt =3D not_found >> endif >=20 >=20 > It first of all checks if fdt.found() returns true, it so, it will check to= compile and build the program in cc.links(=E2=80=A6). I assume that the func= tion fdt_find_max_phandle() does not exitt before version 1.5.1 and therefore= the program should not build with older versions. Then it will move to the = =E2=80=9Celif fdt_opt =3D=3D =E2=80=99system=E2=80=99=E2=80=9D part and compl= ain that the library that is already installed is incompatible. >=20 > So the check should work and actually do something. >=20 > Whenever a program bundles a library, we should remove it. Bundles librarie= s are evil because lets say there is a problem in libfdt, we will patch the p= ackage, but we don=E2=80=99t know what other programs bring their own version= which won=E2=80=99t receive the fix. This is particularly bad for anything s= ecurity-related as parts of the distribution will still be vulnerable. Then when I am doing my package updates if I see any bundled stuff then I wil= l check how to use a system version instead. >=20 > Shared libraries (like libfdt.so .N) are nicer because t= hey can be pulled in by any program that needs the functionality and can be r= eplaced with an improved version without any regard of what programs link aga= inst it - for as long as there are no breaking changes. >=20 > Rust for example is going the opposite way where everything is statically l= inked which is a security nightmare as described above. Every program that us= es a vulnerable crate will have to be rebuilt. But how do you find them all? >=20 > There is more about bundles libraries here: https://fedoraproject.org/wiki/= Bundled_Libraries >=20 >> Can you have a check through this following code and see if my interpretat= ion is correct or if I have just misunderstood how the code is supposed to be= working. >> >> It also looks like the check for the fdt code being internal has not been = removed from it even though dtc is no longer bundled with qemu. >=20 > In that case, we should set fdt=3Dsystem just to make sure that QEMU does t= he right thing during the build. Okay, I will try that and see what happens. >=20 > Did I not merge any patches yesterday? Is that version not affected? Yes, you did but that was for version 9.0.0 which still had the bundled dtc. = I thought it was still worth updating as there have been 11 update versions s= ince the 8.2.1 version we currently have in stable. I will also have a look at the other packages they have in the subprojects di= rectory to see if our build uses any of them. Regards, Adolf. >=20 > -Michael >=20 >> fdt =3D not_found >> fdt_opt =3D get_option('fdt') >> if fdt_required.length() > 0 or fdt_opt =3D=3D 'enabled' >> if fdt_opt =3D=3D 'disabled' >> error('fdt disabled but required by targets ' + ', '.join(fdt_require= d)) >> endif >> >> if fdt_opt in ['enabled', 'auto', 'system'] >> if get_option('wrap_mode') =3D=3D 'nodownload' >> fdt_opt =3D 'system' >> endif >> fdt =3D cc.find_library('fdt', required: fdt_opt =3D=3D 'system') >> if fdt.found() and cc.links(''' >> #include >> #include >> int main(void) { fdt_find_max_phandle(NULL, NULL); return 0; }''', >> dependencies: fdt) >> fdt_opt =3D 'system' >> elif fdt_opt =3D=3D 'system' >> error('system libfdt requested, but it is too old (1.5.1 or newer = required)') >> else >> fdt_opt =3D 'internal' >> fdt =3D not_found >> endif >> endif >> if not fdt.found() >> assert(fdt_opt =3D=3D 'internal') >> libfdt_proj =3D subproject('dtc', required: true, >> default_options: ['tools=3Dfalse', 'yaml=3Dd= isabled', >> 'python=3Ddisabled', 'defa= ult_library=3Dstatic']) >> fdt =3D libfdt_proj.get_variable('libfdt_dep') >> endif >> else >> fdt_opt =3D 'disabled' >> endif >> >> >>> It looks like qemu can correctly detect the presence of libfdt but not th= e version number. >>> >>> I have raised this as an issue in the qemu gitlab site. >>> >>> Version 9.0.0 still had the dtc subproject included in the source tarball= , so I am currently building that and have left the IPFire dtc where it was f= or the moment. >>> >>> This will still update qemu by 11 version numbers. >>> >>> I will wait to see what response I get back from the qemu team for updati= ng to 9.0.2 >>> >>> Regards, >>> Adolf. >>> >>>> >>>> -Michael >>>> >>>>> On 2 Sep 2024, at 19:46, Adolf Belka wrote: >>>>> >>>>> Hi All, >>>>> >>>>> I am trying to do an update of the qemu package. >>>>> >>>>> It is failing for a missing fdt library which it says is required by ta= rgets x86_64-softmmu, aarch64-softmmu and riscv64-softmmu. >>>>> >>>>> The previous version that we currently have, 8.1.2 has a bundled dtc wh= ich includes the fdt library. That has been removed, probably with the change= to the 9.x branch as it is not in 9.0.2 >>>>> >>>>> We have the dtc package in make but it is after qemu. >>>>> >>>>> I could move it to before qemu, however I also note that the dtc packag= e is specified only for aarch64 but if we need to have the above softmmu targ= ets specified then qemu is requiring the fdt library for all our architecture= s. >>>>> >>>>> Before I move dtc and change it to be for all architectures, I just wan= t to flag this up and confirm that it is the right thing to do. >>>>> >>>>> Regards, >>>>> >>>>> Adolf. >=20 >=20 --===============6095632298780699970==--