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lib/systems: unify ARMv5 platforms with stock kernel configuration

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The `sheevaplug` kernel configuration was added a very long time
ago and has not been adjusted for years. `pogoplug4` was identical
to `sheevaplug` except for an even more stripped‐down kernel
configuration, no device tree support, and a different load address
for the uImage.

These days, the stock kernel configuration builds and there has been
an upstream device tree for the Pogoplug Series 4 for years; unify
`sheevaplug` and `pogoplug4` into an `armv5tel-multiplatform` that
uses the standard configuration.

ARMv5 was also the only platform that defaulted to uImage, the [legacy
U‐Boot image format] that is deprecated upstream. Our bootloader
machinery in NixOS does not handle these images in any special way
and even the original ARMv6 Raspberry Pi platform defaults to the
standard zImage. We switch `armv5tel-multiplatform` to zImage to match.

[legacy U‐Boot image format]: https://docs.u-boot.org/en/latest/usage/cmd/bootm.html#legacy-boot

It is of course natural to worry about backwards compatibility
here: this switches to a different kernel image format and drops
support for root on NFS along with random oddities like KGDB and
LatencyTOP. Renaming the platform is intended to help mitigate
this risk.

The reality, however, is that it is currently very
difficult to build a configuration for ARMv5. I found
<https://github.com/thefloweringash/sheevaplug-nix> online as
an example configuration from many years ago; it already set
`autoModules`, and builds U‐Boot using `CONFIG_DISTRO_DEFAULTS`,
which should work out of the box without requiring the legacy U‐Boot
image format.

Even then, however, I confirmed with the author that it hasn’t
been used in years, and I could barely get it to build with
a modern Nixpkgs: OpenSSH is broken, Nix is broken, multiple
default `environment.systemPackages` in the SD image profile
are broken, `boot.initrd.includeDefaultModules` is broken, and
`hardware.enableAllHardware` is broken.

I conclude that if anyone is actively building systems on ARMv5, they
have a forked Nixpkgs or a very custom setup. Given our general move
to standard boot chains and no platform‐specific hacks, and the
decaying state of our unofficial support for 32‐bit ARM, I think
it is not worth maintaining support for the legacy image format for
this one ancient platform.

If anyone is running a heavily stripped‐down NixOS configuration on
mission‐critical SheevaPlugs using a custom Nix‐free deployment
setup relying on the legacy U‐Boot image format and somehow none
of these kernel changes manage to loudly break their build, hopefully
they’ll at least notice the release notes entry! Otherwise there’s
always JTAG…
This commit is contained in:
Emily
2025-06-24 18:56:51 +01:00
committed by zowoq
parent af6485561c
commit 0c19eb3e55
6 changed files with 17 additions and 144 deletions
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10
lib/systems/examples.nix
View File

@@ -40,10 +40,9 @@ rec {
rust.rustcTarget = "powerpc-unknown-linux-gnu";
};
sheevaplug = {
armv5tel-multiplatform = {
config = "armv5tel-unknown-linux-gnueabi";
}
// platforms.sheevaplug;
};
raspberryPi = {
config = "armv6l-unknown-linux-gnueabihf";
@@ -99,11 +98,6 @@ rec {
useLLVM = true;
};
pogoplug4 = {
config = "armv5tel-unknown-linux-gnueabi";
}
// platforms.pogoplug4;
ben-nanonote = {
config = "mipsel-unknown-linux-uclibc";
}

137
lib/systems/platforms.nix
View File

@@ -46,138 +46,15 @@ rec {
## ARM
##
pogoplug4 = {
armv5tel-multiplatform = {
linux-kernel = {
name = "pogoplug4";
name = "armv5tel-multiplatform";
baseConfig = "multi_v5_defconfig";
autoModules = false;
extraConfig = ''
# Ubi for the mtd
MTD_UBI y
UBIFS_FS y
UBIFS_FS_XATTR y
UBIFS_FS_ADVANCED_COMPR y
UBIFS_FS_LZO y
UBIFS_FS_ZLIB y
UBIFS_FS_DEBUG n
'';
makeFlags = [ "LOADADDR=0x8000" ];
target = "uImage";
# TODO reenable once manual-config's config actually builds a .dtb and this is checked to be working
#DTB = true;
};
gcc = {
arch = "armv5te";
};
};
sheevaplug = {
linux-kernel = {
name = "sheevaplug";
baseConfig = "multi_v5_defconfig";
autoModules = false;
extraConfig = ''
BLK_DEV_RAM y
BLK_DEV_INITRD y
BLK_DEV_CRYPTOLOOP m
BLK_DEV_DM m
DM_CRYPT m
MD y
BTRFS_FS m
XFS_FS m
JFS_FS m
EXT4_FS m
USB_STORAGE_CYPRESS_ATACB m
# mv cesa requires this sw fallback, for mv-sha1
CRYPTO_SHA1 y
# Fast crypto
CRYPTO_TWOFISH y
CRYPTO_TWOFISH_COMMON y
CRYPTO_BLOWFISH y
CRYPTO_BLOWFISH_COMMON y
IP_PNP y
IP_PNP_DHCP y
NFS_FS y
ROOT_NFS y
TUN m
NFS_V4 y
NFS_V4_1 y
NFS_FSCACHE y
NFSD m
NFSD_V2_ACL y
NFSD_V3 y
NFSD_V3_ACL y
NFSD_V4 y
NETFILTER y
IP_NF_IPTABLES y
IP_NF_FILTER y
IP_NF_MATCH_ADDRTYPE y
IP_NF_TARGET_LOG y
IP_NF_MANGLE y
IPV6 m
VLAN_8021Q m
CIFS y
CIFS_XATTR y
CIFS_POSIX y
CIFS_FSCACHE y
CIFS_ACL y
WATCHDOG y
WATCHDOG_CORE y
ORION_WATCHDOG m
ZRAM m
NETCONSOLE m
# Disable OABI to have seccomp_filter (required for systemd)
# https://github.com/raspberrypi/firmware/issues/651
OABI_COMPAT n
# Fail to build
DRM n
SCSI_ADVANSYS n
USB_ISP1362_HCD n
SND_SOC n
SND_ALI5451 n
FB_SAVAGE n
SCSI_NSP32 n
ATA_SFF n
SUNGEM n
IRDA n
ATM_HE n
SCSI_ACARD n
BLK_DEV_CMD640_ENHANCED n
FUSE_FS m
# systemd uses cgroups
CGROUPS y
# Latencytop
LATENCYTOP y
# Ubi for the mtd
MTD_UBI y
UBIFS_FS y
UBIFS_FS_XATTR y
UBIFS_FS_ADVANCED_COMPR y
UBIFS_FS_LZO y
UBIFS_FS_ZLIB y
UBIFS_FS_DEBUG n
# Kdb, for kernel troubles
KGDB y
KGDB_SERIAL_CONSOLE y
KGDB_KDB y
'';
makeFlags = [ "LOADADDR=0x0200000" ];
target = "uImage";
DTB = true; # Beyond 3.10
DTB = true;
autoModules = true;
preferBuiltin = true;
target = "zImage";
};
gcc = {
arch = "armv5te";
@@ -407,7 +284,7 @@ rec {
if version == null then
pc
else if lib.versionOlder version "6" then
sheevaplug
armv5tel-multiplatform
else if lib.versionOlder version "7" then
raspberrypi
else