Module Name: src
Committed By: martin
Date: Wed Aug 14 12:49:38 UTC 2019
Added Files:
src/usr.sbin/sysinst: README.md_defs
Log Message:
Provide some documentation for macros / defines used in the machine
dependent backend parts of sysinst.
To generate a diff of this commit:
cvs rdiff -u -r0 -r1.1 src/usr.sbin/sysinst/README.md_defs
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Added files:
Index: src/usr.sbin/sysinst/README.md_defs
diff -u /dev/null src/usr.sbin/sysinst/README.md_defs:1.1
--- /dev/null Wed Aug 14 12:49:38 2019
+++ src/usr.sbin/sysinst/README.md_defs Wed Aug 14 12:49:37 2019
@@ -0,0 +1,85 @@
+/* $NetBSD: README.md_defs,v 1.1 2019/08/14 12:49:37 martin Exp $ */
+
+The following is trying to document the most important machine dependent
+defines used in the sysinst code.
+
+
+If HAVE_GPT is true, the MD code may limit the space used for the
+GPT at the beginning of the disk to allow e.g. a bootloader
+being added after it (see evbarm on allwinner SoCs, u-boot is
+copied at 8k into the image).
+
+/* Size limit for the initial GPT part, in bytes */
+#define MD_GPT_INITIAL_SIZE (8*1024)
+
+
+The default installation description is created as a static array using
+lots of conditionals. It may be overriden / replaced in the MD code
+(see below), an example for that is arch/i386/md.c when we have been
+booted from UEFI firmware.
+
+Name Value / example Description
+PART_BOOT (8*MEG) (undefined) if defined, a boot partition
+ of this size (in bytes, rounded)
+ will be part of the default partition
+ suggestions. Must be compile time
+ const! Use MD_PART_DEFAULTS if
+ runtime adjustment is needed.
+PART_BOOT_MOUNT "/boot" (undefined) Add boot partition to fstab for
+ this mount point
+PART_BOOT_TYPE FS_BSDFS Kind of filesystem used
+PART_BOOT_SUBT MBR_PTYPE_FAT12 File system specific sub type
+
+
+The boot partition is always inserted at the front of the suggested default
+partitions, to cope with firmwares that may not be able to load from the
+whole disk.
+
+If multiple boot partitions are required (see ofppc, where various schemes
+are supported, depending on exact model), the variables above can all be
+repeated with _BOOT1_ or _BOOT2_ name instead of _BOOT_.
+
+
+ATTENTION:
+ PART_BOOT is in BYTE (not MB), while most other sizes
+ (DEFROOTSIZE, DEFSWAP, ...) are in MB!
+
+
+The following macros provide optional MD hooks:
+
+MD_PART_DEFAULTS may be undefined
+
+used like:
+
+ void MD_PART_DEFAULTS(struct pm_dev*, struct part_usage_info*,
+ size_t num_usage_infos),
+
+Called before any of the partition usage defaults is ever used, can be used
+to adjust e.g. partition sizes to actual system requirements (align boot
+partition with cylindersize), or (since it is a macro and all params are
+by references) to completely swap the defaults (e.g. EFI vs. biosboot).
+If swapping, make sure allocation and num_usage_infos stays consistent,
+old allocation is done by calloc(3), use free(3) to release.
+
+
+MD_NEED_BOOTBLOCK may be undefined
+
+used like:
+
+ bool MD_NEED_BOOTBLOCK(struct install_partition_desc *install)
+
+returns true if this setup needs boot blocks. Used for example on x86
+when UEFI installs do not need any bootblocks, but BIOS ones do.
+
+
+HAVE_PLAIN_DISKLABEL_BOOT may be undefined, only used on architectures
+ that have MBR as primary with disklabel as
+ secondary partitioning scheme (RAW_PART != 2)
+
+used like:
+
+ bool HAVE_PLAIN_DISKLABEL_BOOT(const char *disk)
+
+returns true if the disk could be made bootable with only a disklabel
+(and no MBR).
+
