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 08:58:21 +0200 Message-ID: <23B802E6-CF76-4EFD-A5A5-29706580D401@ipfire.org> In-Reply-To: <4f14ddd0-4f1c-4be5-8973-bcf0389861bf@ipfire.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1540990077570322033==" List-Id: --===============1540990077570322033== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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 just = didn=E2=80=99t do that since we didn=E2=80=99t have any use for it apart from= aarch64. >>>=20 >>> Move it wherever you want. It should not have any further dependencies. W= e can build it for all architectures. >>=20 >> I did that and qemu found libfdt but then said that it was too old and tha= t a min of 1.5.1 was required but the updated version of dtc I had built was = version 1.7.1 >>=20 > I have found the section in meson.build where it checks for the fdt library= and it seems to me that the code says that if the system fdt is being used t= hen say that it is too old. I can't see any actual check of the version numbe= r of libfdt. Hmm, the code is not the cleanest, but it should perform a few checks before = 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 re= quired)') > 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 to c= ompile and build the program in cc.links(=E2=80=A6). I assume that the functi= on fdt_find_max_phandle() does not exitt before version 1.5.1 and therefore t= he 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 complain= 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 libraries = are evil because lets say there is a problem in libfdt, we will patch the pac= kage, but we don=E2=80=99t know what other programs bring their own version w= hich won=E2=80=99t receive the fix. This is particularly bad for anything sec= urity-related as parts of the distribution will still be vulnerable. Shared libraries (like libfdt.so .N) are nicer because the= y can be pulled in by any program that needs the functionality and can be rep= laced with an improved version without any regard of what programs link again= st it - for as long as there are no breaking changes. Rust for example is going the opposite way where everything is statically lin= ked which is a security nightmare as described above. Every program that uses= 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/Bu= ndled_Libraries > Can you have a check through this following code and see if my interpretati= on is correct or if I have just misunderstood how the code is supposed to be = working. >=20 > It also looks like the check for the fdt code being internal has not been r= emoved 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. Did I not merge any patches yesterday? Is that version not affected? -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_required)) > 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 re= quired)') > 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=3Ddis= abled', > 'python=3Ddisabled', 'defaul= t_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 the= 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 tarball,= so I am currently building that and have left the IPFire dtc where it was fo= r 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 updatin= g 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 tar= gets x86_64-softmmu, aarch64-softmmu and riscv64-softmmu. >>>>=20 >>>> The previous version that we currently have, 8.1.2 has a bundled dtc whi= ch 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 >>>>=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 package= is specified only for aarch64 but if we need to have the above softmmu targe= ts specified then qemu is requiring the fdt library for all our architectures. >>>>=20 >>>> Before I move dtc and change it to be for all architectures, I just want= to flag this up and confirm that it is the right thing to do. >>>>=20 >>>> Regards, >>>>=20 >>>> Adolf. --===============1540990077570322033==--