Merge pull request #21290 from poettering/arch-me-harder
some docs/tweaks regarding porting to new archs
This commit is contained in:
Luca Boccassi
@@ -306,11 +306,9 @@ installation processes of Linux a bit more robust and self-descriptive.
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### Why did you only define the root partition for these listed architectures?
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The automatic discovery of the root partition is defined to operate on the disk
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containing the current EFI System Partition (ESP). Since EFI only exists on
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x86, x86-64, ia64, ARM, LoongArch and RISC-V so far, we only defined root
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partition UUIDs for these architectures. Should EFI become more common on
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other architectures, we can define additional UUIDs for them.
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Please submit a patch that adds appropriate partition type UUIDs for the
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architecture of your choice should they be missing so far. The only reason they
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aren't defined yet is that nobody submitted them yet.
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### Why define distinct root partition UUIDs for the various architectures?
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@@ -0,0 +1,61 @@
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---
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title: Porting to New Architectures
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category: Contributing
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layout: default
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SPDX-License-Identifier: LGPL-2.1-or-later
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---
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# Porting systemd to New Architectures
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Here's a brief checklist of things to implement when porting systemd to a new
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architecture.
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1. Patch
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[src/basic/architecture.h](https://github.com/systemd/systemd/blob/main/src/basic/architecture.h)
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and
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[src/basic/architecture.c](https://github.com/systemd/systemd/blob/main/src/basic/architecture.c)
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to make your architecture known to systemd. Besides an `ARCHITECTURE_XYZ`
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enumeration entry you need to provide an implementation of
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`native_architecture()` and `uname_architecture()`.
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2. Patch
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[src/shared/gpt.h](https://github.com/systemd/systemd/blob/main/src/shared/gpt.h)
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and
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[src/shared/gpt.c](https://github.com/systemd/systemd/blob/main/src/shared/gpt.c)
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and define a new set of GPT partition type UUIDs for the root file system,
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`/usr/` file system, and the matching Verity and Verity signature
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partitions. Use `systemd-id128 new -p` to generate new suitable UUIDs you
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can use for this. Make sure to register your new types in the various
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functions in `gpt.c`. Also make sure to update the tables in
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`docs/DISCOVERABLE_PARTITIONS.md` and `man/systemd-gpt-auto-generator.xml`
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accordingly.
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3. If your architecture supports UEFI, make sure to update the `efi_arch`
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variable logic in `meson.build` to be set to the right architecture string
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as defined by the UEFI specification. (This ensures that `systemd-boot` will
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be built as the appropriately named `BOOT<arch>.EFI` binary.) Also, if your
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architecture uses a special boot protocol for the Linux kernel make sure to
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implement it in `src/boot/efi/linux*.c`, so that the `systemd-stub` EFI stub
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can work.
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4. Make sure to register the right system call numbers for your architecture in
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`src/basic/missing_syscall_def.h`. systemd uses various system calls the
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Linux kernel provides that are currently not wrapped by glibc (or are only
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in very new glibc), and we need to know the right numbers for them. It might
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also be necessary to tweak `src/basic/raw-clone.h`.
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5. Make sure the code in `src/shared/seccomp-util.c` properly understands the
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local architecture and its system call quirks.
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6. If your architecture uses a `/lib64/` library directory, then make sure that
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the `BaseFilesystem` table in `src/shared/base-filesystem.c` has an entry
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for it so that it can be set up automatically if missing. This is useful to
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support booting into OS trees that have an empty root directory with only
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`/usr/` mounted in.
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7. If your architecture has a CPU opcode similar to x86' RDRAND consider adding
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native support for it to `src/basic/random-util.c`'s `rdrand()` function.
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8. If your architecture supports VM virtualization and provides CPU opcodes
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similar to x86' CPUID consider adding native support for detecting VMs this
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way to `src/basic/virt.c`.
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@@ -106,8 +106,7 @@ int uname_architecture(void) {
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{ "crisv32", ARCHITECTURE_CRIS },
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#elif defined(__nios2__)
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{ "nios2", ARCHITECTURE_NIOS2 },
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#elif defined(__riscv__) || defined(__riscv)
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/* __riscv__ is obsolete, remove in 2018 */
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#elif defined(__riscv)
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{ "riscv32", ARCHITECTURE_RISCV32 },
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{ "riscv64", ARCHITECTURE_RISCV64 },
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# if __SIZEOF_POINTER__ == 4
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@@ -210,8 +210,7 @@ int uname_architecture(void);
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#elif defined(__nios2__)
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# define native_architecture() ARCHITECTURE_NIOS2
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# define LIB_ARCH_TUPLE "nios2-linux-gnu"
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#elif defined(__riscv__) || defined(__riscv)
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/* __riscv__ is obsolete, remove in 2018 */
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#elif defined(__riscv)
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# if __SIZEOF_POINTER__ == 4
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# define native_architecture() ARCHITECTURE_RISCV32
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# define LIB_ARCH_TUPLE "riscv32-linux-gnu"
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@@ -20,10 +20,10 @@
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#include "user-util.h"
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typedef struct BaseFilesystem {
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const char *dir;
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const char *dir; /* directory or symlink to create */
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mode_t mode;
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const char *target;
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const char *exists;
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const char *target; /* if non-NULL create as symlink to this target */
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const char *exists; /* conditionalize this entry on existance of this file */
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bool ignore_failure;
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} BaseFilesystem;
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@@ -39,11 +39,26 @@ static const BaseFilesystem table[] = {
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{ "sys", 0755, NULL, NULL, true },
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{ "dev", 0755, NULL, NULL, true },
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#if defined(__i386__) || defined(__x86_64__)
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/* Various architecture ABIs define the path to the dynamic loader via the /lib64/ subdirectory of
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* the root directory. When booting from an otherwise empty root file system (where only /usr/ has
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* been mounted into) it is thus necessary to create a symlink pointing to the right subdirectory of
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* /usr/ first — otherwise we couldn't invoke any dynamic binary. Let's detect this case here, and
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* create the symlink as needed should it be missing. We prefer doing this consistently with Debian's
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* multiarch logic, but support Fedora-style multilib too.*/
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{ "lib64", 0, "usr/lib/x86_64-linux-gnu\0"
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"usr/lib64\0", "ld-linux-x86-64.so.2" },
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#else
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/* gcc doesn't allow pragma to be used within constructs, hence log about this separately below */
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# define WARN_LIB64 1
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#endif
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};
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#ifdef WARN_LIB64
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#pragma message "If your architecture knows a /lib64/ or /lib32/ directory, please add an entry creating it here."
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/* And if your architecture doesn't know these directories, make sure to add ifdeffery here to
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* suppress this pragma message. */
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#endif
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int base_filesystem_create(const char *root, uid_t uid, gid_t gid) {
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_cleanup_close_ int fd = -1;
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int r;
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@@ -4,6 +4,16 @@
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#include "string-util.h"
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#include "utf8.h"
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/* Gently push people towards defining GPT type UUIDs for all architectures we know */
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#if !defined(GPT_ROOT_NATIVE) || \
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!defined(GPT_ROOT_NATIVE_VERITY) || \
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!defined(GPT_ROOT_NATIVE_VERITY_SIG) || \
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!defined(GPT_USR_NATIVE) || \
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!defined(GPT_USR_NATIVE_VERITY) || \
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!defined(GPT_USR_NATIVE_VERITY_SIG)
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#pragma message "Please define GPT partition types for your architecture."
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#endif
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const GptPartitionType gpt_partition_type_table[] = {
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{ GPT_ROOT_X86, "root-x86" },
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{ GPT_ROOT_X86_VERITY, "root-x86-verity" },
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