linux: ability to merge structured configs

This should make the composability of kernel configurations more straigthforward.

- now distinguish freeform options from tristate ones
- will look for a structured config in kernelPatches too
one can now access the structuredConfig from a kernel via linux_test.configfile.structuredConfig
in order to reinject it into another kernel, no need to rewrite the config from scratch

The following merge strategies are used in case of conflict:
-- freeform items must be equal or they conflict (mergeEqualOption)
-- for tristate (y/m/n) entries, I use the mergeAnswer strategy which takes the best available value, "best" being defined by the user (by default "y" > "m" > "n", e.g. if one entry is both marked "y" and "n", "y" wins)
-- if one item is both marked optional/mandatory, mandatory wins (mergeFalseByDefault)

1 files changed, 31 insertions, 36 deletions

diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index ddd1e9828d5..bdcad8c2383 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -12,25 +12,19 @@
 # Configuration
 { stdenv, version
 
-# to let user override values, aka converting modules to included and vice-versa
-, mkValueOverride ? null
-
-# new extraConfig as a flattened set
-, structuredExtraConfig ? {}
-
-# legacy extraConfig as string
-, extraConfig ? ""
-
 , features ? { grsecurity = false; xen_dom0 = false; }
 }:
 
-assert (mkValueOverride == null) || (builtins.isFunction mkValueOverride);
-
 with stdenv.lib;
 
-with import ../../../../lib/kernel.nix { inherit (stdenv) lib; inherit version; };
+  with import ../../../../lib/kernel.nix { inherit (stdenv) lib; };
 
 let
+  # Common patterns/legacy
+  when = cond: opt: if cond then opt else null;
+  whenAtLeast = ver: mkIf (versionAtLeast version ver);
+  whenOlder   = ver: mkIf (versionOlder version ver);
+  whenBetween = verLow: verHigh: mkIf (versionAtLeast version verLow && versionOlder version verHigh);
 
   # configuration items have to be part of a subattrs
   flattenKConf =  nested: mapAttrs (_: head) (zipAttrs (attrValues nested));
@@ -46,7 +40,7 @@ let
       DEBUG_NX_TEST             = whenOlder "4.11" no;
       CPU_NOTIFIER_ERROR_INJECT = whenOlder "4.4" (option no);
       DEBUG_STACK_USAGE         = no;
-      DEBUG_STACKOVERFLOW       = when (!features.grsecurity) no;
+      DEBUG_STACKOVERFLOW       = mkIf (!features.grsecurity) no;
       RCU_TORTURE_TEST          = no;
       SCHEDSTATS                = no;
       DETECT_HUNG_TASK          = yes;
@@ -114,7 +108,7 @@ let
       IP_DCCP_CCID3      = no; # experimental
       CLS_U32_PERF       = yes;
       CLS_U32_MARK       = yes;
-      BPF_JIT            = when (stdenv.hostPlatform.system == "x86_64-linux") yes;
+      BPF_JIT            = mkIf (stdenv.hostPlatform.system == "x86_64-linux") yes;
       WAN                = yes;
       # Required by systemd per-cgroup firewalling
       CGROUP_BPF                  = option yes;
@@ -184,7 +178,7 @@ let
       FB_VESA             = yes;
       FRAMEBUFFER_CONSOLE = yes;
       FRAMEBUFFER_CONSOLE_ROTATION = yes;
-      FB_GEODE            = when (stdenv.hostPlatform.system == "i686-linux") yes;
+      FB_GEODE            = mkIf (stdenv.hostPlatform.system == "i686-linux") yes;
     };
 
     video = {
@@ -239,7 +233,7 @@ let
     };
 
     usb = {
-      USB_DEBUG            = option (whenOlder "4.18" no);
+      USB_DEBUG = { optional = true; tristate = whenOlder "4.18" "n";};
       USB_EHCI_ROOT_HUB_TT = yes; # Root Hub Transaction Translators
       USB_EHCI_TT_NEWSCHED = yes; # Improved transaction translator scheduling
     };
@@ -250,7 +244,7 @@ let
       FANOTIFY        = yes;
       TMPFS           = yes;
       TMPFS_POSIX_ACL = yes;
-      FS_ENCRYPTION   = option (whenAtLeast "4.9" module);
+      FS_ENCRYPTION   = { optional = true; tristate = whenAtLeast "4.9" "m"; };
 
       EXT2_FS_XATTR     = yes;
       EXT2_FS_POSIX_ACL = yes;
@@ -262,7 +256,7 @@ let
 
       EXT4_FS_POSIX_ACL = yes;
       EXT4_FS_SECURITY  = yes;
-      EXT4_ENCRYPTION   = option ((if (versionOlder version "4.8") then module else yes));
+      EXT4_ENCRYPTION   = { optional = true; tristate = if (versionOlder version "4.8") then "m" else "y"; };
 
       REISERFS_FS_XATTR     = option yes;
       REISERFS_FS_POSIX_ACL = option yes;
@@ -324,7 +318,7 @@ let
 
       # Native Language Support modules, needed by some filesystems
       NLS              = yes;
-      NLS_DEFAULT      = "utf8";
+      NLS_DEFAULT      = freeform "utf8";
       NLS_UTF8         = module;
       NLS_CODEPAGE_437 = module; # VFAT default for the codepage= mount option
       NLS_ISO8859_1    = module; # VFAT default for the iocharset= mount option
@@ -334,13 +328,13 @@ let
 
     security = {
       # Detect writes to read-only module pages
-      DEBUG_SET_MODULE_RONX            = option (whenOlder "4.11" yes);
+      DEBUG_SET_MODULE_RONX            = { optional = true; tristate = whenOlder "4.11" "y"; };
       RANDOMIZE_BASE                   = option yes;
       STRICT_DEVMEM                    = option yes; # Filter access to /dev/mem
-      SECURITY_SELINUX_BOOTPARAM_VALUE = "0"; # Disable SELinux by default
+      SECURITY_SELINUX_BOOTPARAM_VALUE = freeform "0"; # Disable SELinux by default
       # Prevent processes from ptracing non-children processes
       SECURITY_YAMA                    = option yes;
-      DEVKMEM                          = when (!features.grsecurity) no; # Disable /dev/kmem
+      DEVKMEM                          = mkIf (!features.grsecurity) no; # Disable /dev/kmem
 
       USER_NS                          = yes; # Support for user namespaces
 
@@ -350,7 +344,7 @@ let
     } // optionalAttrs (!stdenv.hostPlatform.isAarch32) {
 
       # Detect buffer overflows on the stack
-      CC_STACKPROTECTOR_REGULAR = option (whenOlder "4.18" yes);
+      CC_STACKPROTECTOR_REGULAR = {optional = true; tristate = whenOlder "4.18" "y";};
     };
 
     microcode = {
@@ -407,8 +401,8 @@ let
       FTRACE_SYSCALLS       = yes;
       SCHED_TRACER          = yes;
       STACK_TRACER          = yes;
-      UPROBE_EVENT          = option (whenOlder "4.11" yes);
-      UPROBE_EVENTS         = option (whenAtLeast "4.11" yes);
+      UPROBE_EVENT          = { optional = true; tristate = whenOlder "4.11" "y";};
+      UPROBE_EVENTS         = { optional = true; tristate = whenAtLeast "4.11" "y";};
       BPF_SYSCALL           = whenAtLeast "4.4" yes;
       BPF_EVENTS            = whenAtLeast "4.4" yes;
       FUNCTION_PROFILER     = yes;
@@ -418,13 +412,13 @@ let
     virtualisation = {
       PARAVIRT = option yes;
 
-      HYPERVISOR_GUEST = when (!features.grsecurity) yes;
+      HYPERVISOR_GUEST = mkIf (!features.grsecurity) yes;
       PARAVIRT_SPINLOCKS  = option yes;
 
       KVM_APIC_ARCHITECTURE             = whenOlder "4.8" yes;
       KVM_ASYNC_PF                      = yes;
-      KVM_COMPAT                        = option (whenBetween "4.0" "4.12"  yes);
-      KVM_DEVICE_ASSIGNMENT             = option (whenBetween "3.10" "4.12" yes);
+      KVM_COMPAT = { optional = true; tristate = whenBetween "4.0" "4.12" "y"; };
+      KVM_DEVICE_ASSIGNMENT  = { optional = true; tristate = whenBetween "3.10" "4.12" "y"; };
       KVM_GENERIC_DIRTYLOG_READ_PROTECT = whenAtLeast "4.0"  yes;
       KVM_GUEST                         = when (!features.grsecurity) yes;
       KVM_MMIO                          = yes;
@@ -432,9 +426,9 @@ let
       KSM = yes;
       VIRT_DRIVERS = yes;
       # We nneed 64 GB (PAE) support for Xen guest support
-      HIGHMEM64G = option (when (!stdenv.is64bit) yes);
+      HIGHMEM64G = { optional = true; tristate = mkIf (!stdenv.is64bit) "y";};
 
-      VFIO_PCI_VGA = when stdenv.is64bit yes;
+      VFIO_PCI_VGA = mkIf stdenv.is64bit yes;
 
     } // optionalAttrs (stdenv.isx86_64 || stdenv.isi686) ({
       XEN = option yes;
@@ -542,8 +536,8 @@ let
       CRYPTO_TEST              = option no;
       EFI_TEST                 = option no;
       GLOB_SELFTEST            = option no;
-      DRM_DEBUG_MM_SELFTEST    = option (whenOlder "4.18" no);
-      LNET_SELFTEST            = option (whenOlder "4.18" no);
+      DRM_DEBUG_MM_SELFTEST    = { optional = true; tristate = whenOlder "4.18" "n";};
+      LNET_SELFTEST            = { optional = true; tristate = whenOlder "4.18" "n";};
       LOCK_TORTURE_TEST        = option no;
       MTD_TESTS                = option no;
       NOTIFIER_ERROR_INJECTION = option no;
@@ -598,7 +592,7 @@ let
       AIC79XX_DEBUG_ENABLE = no;
       AIC7XXX_DEBUG_ENABLE = no;
       AIC94XX_DEBUG = no;
-      B43_PCMCIA = option (whenOlder "4.4" yes);
+      B43_PCMCIA = { optional=true; tristate = whenOlder "4.4" "y";};
 
       BLK_DEV_INTEGRITY       = yes;
 
@@ -651,7 +645,7 @@ let
       # GPIO on Intel Bay Trail, for some Chromebook internal eMMC disks
       PINCTRL_BAYTRAIL   = yes;
       # 8 is default. Modern gpt tables on eMMC may go far beyond 8.
-      MMC_BLOCK_MINORS   = "32";
+      MMC_BLOCK_MINORS   = freeform "32";
 
       REGULATOR  = yes; # Voltage and Current Regulator Support
       RC_DEVICES = option yes; # Enable IR devices
@@ -698,7 +692,8 @@ let
 
       # Bump the maximum number of CPUs to support systems like EC2 x1.*
       # instances and Xeon Phi.
-      NR_CPUS = "384";
+      NR_CPUS = freeform "384";
     };
   };
-in (generateNixKConf ((flattenKConf options) // structuredExtraConfig) mkValueOverride) + extraConfig
+in
+  flattenKConf options