On Thu, 5 Dec 2019 at 16:27, Philippe Mathieu-Daudé <phi...@redhat.com> wrote: > > On 12/5/19 5:13 PM, Laszlo Ersek wrote: > > Hi Phil, > > > > (+Ard) > > > > On 12/04/19 23:12, Philippe Mathieu-Daudé wrote: > >> Centos 7.7 only provides cross GCC 4.8.5, but the script forces > >> us to use GCC5. Since the same machinery is valid to check the > >> GCC version, remove the $emulation_target check. > >> > >> $ cat /etc/redhat-release > >> CentOS Linux release 7.7.1908 (Core) > >> > >> $ aarch64-linux-gnu-gcc -v 2>&1 | tail -1 > >> gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) > > > > this patch is not correct, in my opinion. ARM / AARCH64 support in edk2 > > requires GCC5 as a minimum. It was never tested with an earlier > > toolchain, to my understanding. Not on my part, anyway. > > > > To be more precise: when I tested cross-gcc toolchains earlier than > > that, the ArmVirtQemu builds always failed. Minimally, those toolchains > > didn't recognize some of the AARCH64 system registers. > > > > If CentOS 7.7 does not provide a suitable (>=GCC5) toolchain, then we > > can't build ArmVirtQemu binaries on CentOS 7.7, in my opinion. > > > > Personally, on my RHEL7 laptop, over time I've used the following > > toolchains, to satisfy the GCC5 requirement of ArmVirtQemu (which > > requirement I took as experimental evidence): > > > > - Initially (last quarter of 2014), I used binary distributions -- > > tarballs -- of cross-binutils and cross-gcc, from Linaro. > > > > - Later (last quarter of 2016), I rebuilt some SRPMs that were at the > > time Fedora-only for RHEL7. Namely: > > > > - cross-binutils-2.27-3.fc24 > > https://koji.fedoraproject.org/koji/buildinfo?buildID=801348 > > > > - gcc-6.1.1-2.fc24 > > https://koji.fedoraproject.org/koji/buildinfo?buildID=761767 > > > > - Most recently, I've been using cross-binutils updated from EPEL7: > > > > - cross-binutils-2.27-9.el7.1 > > https://koji.fedoraproject.org/koji/buildinfo?buildID=918474 > > > > To my knowledge, there is still no suitable cross-compiler available on > > RHEL7, from any trustworthy RPM repository. So, to this day, I use > > gcc-6.1.1-2 for cross-building ArmVirtQemu, on my RHEL7 laptop. > > > > Again: I believe it does not matter if the gcc-4.8.5-based > > cross-compiler in CentOS 7 "happens" to work. That's a compiler that I > > have never tested with, or vetted for, upstream ArmVirtQemu. > > > > Now, I realize that in edk2, we have stuff like > > > > GCC48_AARCH64_CC_FLAGS > > > > in "BaseTools/Conf/tools_def.template" -- coming from commit > > 7a9dbf2c94d1 ("BaseTools/Conf/tools_def.template: drop ARM/AARCH support > > from GCC46/GCC47", 2019-01-08). That doesn't change the fact that I've > > never built or tested ArmVirtQemu with such a compiler. And so this > > patch makes me quite uncomfortable. > > > > If that rules out CentOS 7 as a QEMU project build / CI platform for the > > bundled ArmVirtQemu binaries, then we need a more recent platform > > (perhaps CentOS 8, not sure). > > Unfortunately CentOS 8 is not available as a Docker image, which is a > convenient way to build EDK2 in a CI. > > > I think it's also educational to check the origin of the code that your > > patch proposes to remove. Most recently it was moved around from a > > different place, in QEMU commit 65a109ab4b1a ('roms: lift > > "edk2-funcs.sh" from "tests/uefi-test-tools/build.sh"', 2019-04-17). > > > > In that commit, for some reason I didn't keep the original code comments > > (perhaps it would have been too difficult or messy to preserve the > > comments sanely with the restructured / factored-out code). But, they > > went like this (originally from commit 77db55fc8155, > > "tests/uefi-test-tools: add build scripts", 2019-02-21): > > > > # Expose cross_prefix (which is possibly empty) to the edk2 tools. While at > > it, > > # determine the suitable edk2 toolchain as well. > > # - For ARM and AARCH64, edk2 only offers the GCC5 toolchain tag, which > > covers > > # the gcc-5+ releases. > > # - For IA32 and X64, edk2 offers the GCC44 through GCC49 toolchain tags, in > > # addition to GCC5. Unfortunately, the mapping between the toolchain tags > > and > > # the actual gcc releases isn't entirely trivial. Run "git-blame" on > > # "OvmfPkg/build.sh" in edk2 for more information. > > # And, because the above is too simple, we have to assign cross_prefix to an > > # edk2 build variable that is specific to both the toolchain tag and the > > target > > # architecture. > > > > So... unless Ard feels it is really totally safe to retro-actively rely > > on the gcc-4.8.5-based compiler in CentOS 7, I'd rather we picked a more > > recent build platform (OS) instead. For example, we build ArmVirtQemu on > > RHEL8 regularly, so that's a reality-based "plus" for CentOS 8. > > > > > > Independently of all of the above, the OVMF toolchain selection logic > > that this patch proposes to reuse with ArmVirtQemu, is *really* > > x86-specific. Please run "git blame" on "OvmfPkg/build.sh" in upstream > > edk2, to see where the various branches come from (as the comments in > > this shell script suggest as well). There had been mess like commit > > 656ac0c7d8ea ('Revert "OvmfPkg/build.sh: select the GCC49 toolchain > > settings for gcc-7.*"', 2017-08-25). > > Thanks for all the pointers, very educative indeed :) > > I'll see other setups I can use with GCC5+ available. > > I still have to figure if there are free tier CI with less limitations > than Travis/Shippable/GitLab, so we can keep the full EDK2 build output log. >
My CI job for ArmVirtQemu/EDK2 build tested GCC48 and GCC49 until very recently, and I never experienced any issues when running those images, although it's been much longer that I actually tried that. So I wouldn't recommend against it, and if we do identify any issues, we should either deprecate GCC48 (for ArmVirtQemu or for AArch64 altogether) or fix them.
