From 5f45f2506d196a5bc969bd7da9ed6511a4764854 Mon Sep 17 00:00:00 2001 From: K900 Date: Fri, 19 Aug 2022 23:55:28 +0300 Subject: [PATCH] linux: better note --- .../linux/kernel/manual-config.nix | 63 +++++++++++++++---- 1 file changed, 52 insertions(+), 11 deletions(-) diff --git a/pkgs/os-specific/linux/kernel/manual-config.nix b/pkgs/os-specific/linux/kernel/manual-config.nix index a7d31de6eb75..2fcd39bf596a 100644 --- a/pkgs/os-specific/linux/kernel/manual-config.nix +++ b/pkgs/os-specific/linux/kernel/manual-config.nix @@ -59,14 +59,6 @@ let ++ optional (lib.versionAtLeast version "4.14") libelf ++ optional (lib.versionAtLeast version "5.13") zstd; - - installkernel = buildPackages.writeShellScriptBin "installkernel" '' - set -e - mkdir -p $4 - cp -av $2 $4 - cp -av $3 $4 - ''; - drvAttrs = config_: kernelConf: kernelPatches: configfile: let config = let attrName = attr: "CONFIG_" + attr; in { @@ -195,10 +187,59 @@ let ++ optional installsFirmware "INSTALL_FW_PATH=$(out)/lib/firmware" ++ optionals buildDTBs ["dtbs_install" "INSTALL_DTBS_PATH=$(out)/dtbs"]; - preInstall = '' + preInstall = let + # All we really need to do here is copy the final image and System.map to $out, + # and use the kernel's modules_install, firmware_install, dtbs_install, etc. targets + # for the rest. Easy, right? + # + # Unfortunately for us, the obvious way of getting the built image path, + # make -s image_name, does not work correctly, because some architectures + # (*cough* aarch64 *cough*) change KBUILD_IMAGE on the fly in their install targets, + # so we end up attempting to install the thing we didn't actually build. + # + # Thankfully, there's a way out that doesn't involve just hardcoding everything. + # + # The kernel has an install target, which runs a pretty simple shell script + # (located at scripts/install.sh or arch/$arch/boot/install.sh, depending on + # which kernel version you're looking at) that tries to do something sensible. + # + # (it would be great to hijack this script immediately, as it has all the + # information we need passed to it and we don't need it to try and be smart, + # but unfortunately, the exact location of the scripts differs between kernel + # versions, and they're seemingly not considered to be public API at all) + # + # One of the ways it tries to discover what "something sensible" actually is + # is by delegating to what's supposed to be a user-provided install script + # located at ~/bin/installkernel. + # + # (the other options are: + # - a distribution-specific script at /sbin/installkernel, + # which we can't really create in the sandbox easily + # - an architecture-specific script at arch/$arch/boot/install.sh, + # which attempts to guess _something_ and usually guesses very wrong) + # + # More specifically, the install script exec's into ~/bin/installkernel, if one + # exists, with the following arguments: + # + # $1: $KERNELRELEASE - full kernel version string + # $2: $KBUILD_IMAGE - the final image path + # $3: System.map - path to System.map file, seemingly hardcoded everywhere + # $4: $INSTALL_PATH - path to the destination directory as specified in installFlags + # + # $2 is exactly what we want, so hijack the script and use the knowledge given to it + # by the makefile overlords for our own nefarious ends. + # + # Note that the makefiles specifically look in ~/bin/installkernel, and + # writeShellScriptBin writes the script to /bin/installkernel, + # so HOME needs to be set to just the store path. + # + # FIXME: figure out a less roundabout way of doing this. + installkernel = buildPackages.writeShellScriptBin "installkernel" '' + cp -av $2 $4 + cp -av $3 $4 + ''; + in '' installFlagsArray+=("-j$NIX_BUILD_CORES") - - # the install scripts expect to find installkernel in ~/bin/installkernel export HOME=${installkernel} '';