From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tremer 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 11:34:40 +0200 Message-ID: <7DD6AED4-8644-4ACE-9FC6-1AA8FCB3FE91@ipfire.org> In-Reply-To: <433079f5-3b7d-404d-90d9-08b51900d044@ipfire.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7491306373747814854==" List-Id: --===============7491306373747814854== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Hello, > On 4 Sep 2024, at 09:22, Adolf Belka wrote: >=20 > Hi Michael, >=20 > On 04/09/2024 08:58, Michael Tremer wrote: >> Hello, >>> On 3 Sep 2024, at 21:06, Adolf Belka wrote: >>>=20 >>> Hi All, >>>=20 >>> On 03/09/2024 15:25, Adolf Belka wrote: >>>> Hi Michael, >>>>=20 >>>> On 03/09/2024 09:24, Michael Tremer wrote: >>>>> Hello Adolf, >>>>>=20 >>>>> Yes, you can make those changes. >>>>>=20 >>>>> dtc is the device tree compiler and it should be quick to build. We jus= t didn=E2=80=99t do that since we didn=E2=80=99t have any use for it apart fr= om aarch64. >>>>>=20 >>>>> Move it wherever you want. It should not have any further dependencies.= We can build it for all architectures. >>>>=20 >>>> I did that and qemu found libfdt but then said that it was too old and t= hat a min of 1.5.1 was required but the updated version of dtc I had built wa= s version 1.7.1 >>>>=20 >>> I have found the section in meson.build where it checks for the fdt libra= ry 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 num= ber of libfdt. >> Hmm, the code is not the cleanest, but it should perform a few checks befo= re it throws that error. The crucial part is here: >>> 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 >> It first of all checks if fdt.found() returns true, it so, it will check t= o compile and build the program in cc.links(=E2=80=A6). I assume that the fun= ction fdt_find_max_phandle() does not exitt before version 1.5.1 and therefor= e 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. >> So the check should work and actually do something. >> Whenever a program bundles a library, we should remove it. Bundles librari= es are evil because lets say there is a problem in libfdt, we will patch the = package, but we don=E2=80=99t know what other programs bring their own versio= n which won=E2=80=99t receive the fix. This is particularly bad for anything = security-related as parts of the distribution will still be vulnerable. >=20 > Then when I am doing my package updates if I see any bundled stuff then I w= ill check how to use a system version instead. >> Shared libraries (like libfdt.so .N) are nicer because = they can be pulled in by any program that needs the functionality and can be = replaced with an improved version without any regard of what programs link ag= ainst it - for as long as there are no breaking changes. >> Rust for example is going the opposite way where everything is statically = linked which is a security nightmare as described above. Every program that u= ses a vulnerable crate will have to be rebuilt. But how do you find them all? >> There is more about bundles libraries here: https://fedoraproject.org/wiki= /Bundled_Libraries >>> Can you have a check through this following code and see if my interpreta= tion is correct or if I have just misunderstood how the code is supposed to b= e working. >>>=20 >>> 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. >> In that case, we should set fdt=3Dsystem just to make sure that QEMU does = the right thing during the build. >=20 > Okay, I will try that and see what happens. For as long as you have built dtc before QEMU this should work fine. >> Did I not merge any patches yesterday? Is that version not affected? >=20 > 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= since the 8.2.1 version we currently have in stable. Ah, that makes sense. > I will also have a look at the other packages they have in the subprojects = directory to see if our build uses any of them. Thank you! -Michael > Regards, >=20 > Adolf. >> -Michael >>> 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 >>>=20 >>> 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 >>>=20 >>>=20 >>>> It looks like qemu can correctly detect the presence of libfdt but not t= he version number. >>>>=20 >>>> I have raised this as an issue in the qemu gitlab site. >>>>=20 >>>> Version 9.0.0 still had the dtc subproject included in the source tarbal= l, so I am currently building that and have left the IPFire dtc where it was = for the moment. >>>>=20 >>>> This will still update qemu by 11 version numbers. >>>>=20 >>>> I will wait to see what response I get back from the qemu team for updat= ing to 9.0.2 >>>>=20 >>>> Regards, >>>> Adolf. >>>>=20 >>>>>=20 >>>>> -Michael >>>>>=20 >>>>>> On 2 Sep 2024, at 19:46, Adolf Belka wrote: >>>>>>=20 >>>>>> Hi All, >>>>>>=20 >>>>>> I am trying to do an update of the qemu package. >>>>>>=20 >>>>>> It is failing for a missing fdt library which it says is required by t= argets x86_64-softmmu, aarch64-softmmu and riscv64-softmmu. >>>>>>=20 >>>>>> The previous version that we currently have, 8.1.2 has a bundled dtc w= hich includes the fdt library. That has been removed, probably with the chang= e to the 9.x branch as it is not in 9.0.2 >>>>>>=20 >>>>>> We have the dtc package in make but it is after qemu. >>>>>>=20 >>>>>> I could move it to before qemu, however I also note that the dtc packa= ge is specified only for aarch64 but if we need to have the above softmmu tar= gets specified then qemu is requiring the fdt library for all our architectur= es. >>>>>>=20 >>>>>> Before I move dtc and change it to be for all architectures, I just wa= nt to flag this up and confirm that it is the right thing to do. >>>>>>=20 >>>>>> Regards, >>>>>>=20 >>>>>> Adolf. --===============7491306373747814854==--