7fb6e78254
As part of the build, we run some instrumentation hooks to gather statistics about the usage of the target/, staging/ and host/ directories, so that we can generate reports for the user, that shows: - for each file, what package installed it, - for each package,the size that it installed. In so doing, we run a double md5 pass on all files of the affected directories (before/after installation). These passes were mostly invisible when we were only scanning target/, but has greatly increased in time now that we also scan staging/ and host/ (but only in the corresponding _CMDS, of course). This md5 was mostly aimed at catching packages that would "cheat" with mtime/atime/ctime somehow. They can't really cheat on md5, though [0]. Timings however speak for themselves, with this defconfig (slightly biggish-but-still-manageable build) [1]. host/ 20965 files 1.2GiB staging/ 4715 files 333MiB target/ 1801 files 44MiB All instrumentation steps, using md5: 19min 27s All instrumentation steps, using mtime: 14min 45s No instrumentation step at all: 14min 31s So, using mtime is an almost-5min improvement, i.e. about 25% faster, while removing all instrumentation steps does not gain that much more... So, we switch to using mtime, because in the end that's still good-enough for our use-case: generating some graphs. It is not mission-critical, and if a graph is slightly off, that's not a biggy. It can anyway be attributed to a broken package's buildsystem, which should get fixed. However, we lose the ability to track directories. Non-empty directories can be tracked back by a bit of scripting, but empty directories are simply not caught. If we were to also look for directories using mtime, we would catch parents of installed files: - /foo/bar/ exists - a package installs /foo/bar/buz - mtime of /foo/bar/ is changed to account for the new file in it. So we do not track directories at all, and we lose empty directories. The existing tracking was mostly happenstance, with the original submission and comments not really accounting for a real use-case. Now, we also change the way we handle symlinks. Previously, we would hash the file pointed to by the symlink. Now, we only look at the mtime of the symlink itself, which still detects modifications. Eventually, this also means that we now no longer need to establish a list before the install step; we can now simply run after the install step, finding any files newer than the build stamp. [0] Yeah, md5 is very weak, but we're not guarding against malicious attacks, just about careless modifications. [1] defconfig used for tests: BR2_arm=y BR2_cortex_a7=y BR2_TOOLCHAIN_EXTERNAL=y BR2_INIT_SYSTEMD=y BR2_PACKAGE_MESA3D=y BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_ETNAVIV=y BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_SWRAST=y BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_VC4=y BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_VIRGL=y BR2_PACKAGE_MESA3D_DRI_DRIVER_SWRAST=y BR2_PACKAGE_MESA3D_OSMESA=y BR2_PACKAGE_MESA3D_OPENGL_ES=y BR2_PACKAGE_SYSTEMD_JOURNAL_GATEWAY=y BR2_PACKAGE_SYSTEMD_BACKLIGHT=y BR2_PACKAGE_SYSTEMD_BINFMT=y BR2_PACKAGE_SYSTEMD_COREDUMP=y BR2_PACKAGE_SYSTEMD_FIRSTBOOT=y BR2_PACKAGE_SYSTEMD_HIBERNATE=y BR2_PACKAGE_SYSTEMD_IMPORTD=y BR2_PACKAGE_SYSTEMD_LOCALED=y BR2_PACKAGE_SYSTEMD_LOGIND=y BR2_PACKAGE_SYSTEMD_MACHINED=y BR2_PACKAGE_SYSTEMD_POLKIT=y BR2_PACKAGE_SYSTEMD_QUOTACHECK=y BR2_PACKAGE_SYSTEMD_RANDOMSEED=y BR2_PACKAGE_SYSTEMD_RFKILL=y BR2_PACKAGE_SYSTEMD_SMACK_SUPPORT=y BR2_PACKAGE_SYSTEMD_SYSUSERS=y BR2_PACKAGE_SYSTEMD_VCONSOLE=y [Peter: tweak commit message, use find -type l] Reported-by: Trent Piepho <tpiepho@impinj.com> Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr> Cc: Trent Piepho <tpiepho@impinj.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Cc: Peter Korsgaard <peter@korsgaard.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com> |
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| boot | ||
| configs | ||
| docs | ||
| fs | ||
| linux | ||
| package | ||
| support | ||
| system | ||
| toolchain | ||
| utils | ||
| .defconfig | ||
| .flake8 | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .gitlab-ci.yml.in | ||
| CHANGES | ||
| Config.in | ||
| Config.in.legacy | ||
| COPYING | ||
| DEVELOPERS | ||
| Makefile | ||
| Makefile.legacy | ||
| README | ||
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at http://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on Freenode IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches