Hello
Some time ago, I added code in x86 secondary bootstrap to allow
booting on GPT partitions inside a RAID 1. It seems I forgot to
commit the support in primary bootstrap, and in the meantime I
deleted the tree with it. I just rewrote the thing, the patch
is below for comment.
The boot priority is as described in x86/boot(8):
1) the first parition with bootme attribute set
2) the partition we booted from, irrelevant here
3) the first bootable partition (FFS, LFS, CCD, CGD)
4) the first partititon
I handled the case where GPT entries are not 128 bytes long,
as UEFI specification allows that. That makes the code larger
and painful to read. Is it worth it?
Index: sys/arch/i386/stand/bootxx/boot1.c
===================================================================
RCS file: /cvsroot/src/sys/arch/i386/stand/bootxx/boot1.c,v
retrieving revision 1.21
diff -U4 -r1.21 boot1.c
--- sys/arch/i386/stand/bootxx/boot1.c 24 Jun 2021 01:23:16 -0000 1.21
+++ sys/arch/i386/stand/bootxx/boot1.c 26 Jun 2023 14:31:22 -0000
@@ -36,10 +36,12 @@
#include <lib/libkern/libkern.h>
#include <biosdisk_ll.h>
#include <sys/param.h>
+#include <sys/uuid.h>
#include <sys/bootblock.h>
#include <sys/disklabel.h>
+#include <sys/disklabel_gpt.h>
#include <dev/raidframe/raidframevar.h> /* For RF_PROTECTED_SECTORS */
#define XSTR(x) #x
#define STR(x) XSTR(x)
@@ -48,8 +50,9 @@
static struct biosdisk_ll d;
const char *boot1(uint32_t, uint64_t *);
+static daddr_t gpt_lookup(daddr_t);
extern void putstr(const char *);
extern struct disklabel ptn_disklabel;
@@ -89,8 +92,17 @@
bios_sector += RF_PROTECTED_SECTORS;
fd = ob();
if (fd != -1)
goto done;
+
+ /*
+ * Test for a GPT inside the RAID
+ */
+ bios_sector += gpt_lookup(bios_sector);
+ fd = ob();
+ if (fd != -1)
+ goto done;
+
/*
* Nothing at the start of the MBR partition, fallback on
* partition 'a' from the disklabel in this MBR partition.
*/
@@ -143,4 +155,145 @@
return EIO;
return 0;
}
+
+static int
+is_unused(struct gpt_ent *ent)
+{
+ const struct uuid unused = GPT_ENT_TYPE_UNUSED;
+
+ return (memcmp(ent->ent_type, &unused, sizeof(unused)) == 0);
+}
+
+static int
+is_bootable(struct gpt_ent *ent)
+{
+ /* GPT_ENT_TYPE_NETBSD_RAID omitted as we are already in a RAID */
+ const struct uuid bootable[] = {
+ GPT_ENT_TYPE_NETBSD_FFS,
+ GPT_ENT_TYPE_NETBSD_LFS,
+ GPT_ENT_TYPE_NETBSD_CCD,
+ GPT_ENT_TYPE_NETBSD_CGD,
+ };
+ int i;
+
+ for (i = 0; i < sizeof(bootable) / sizeof(*bootable); i++) {
+ if (memcmp(ent->ent_type, &bootable[i],
+ sizeof(struct uuid)) == 0)
+ return 1;
+ }
+
+ return 0;
+}
+
+
+static daddr_t
+gpt_lookup(daddr_t sector)
+{
+ char buf[DEV_BSIZE];
+ struct mbr_sector *pmbr;
+ const char gpt_hdr_sig[] = GPT_HDR_SIG;
+ struct gpt_hdr *hdr;
+ struct gpt_ent *ent;
+ uint32_t nents;
+ uint32_t entsz;
+ uint32_t entries_per_sector;
+ uint32_t sectors_per_entry;
+ uint64_t firstpart_lba = 0;
+ uint64_t bootable_lba = 0;
+ uint64_t bootme_lba = 0;
+ int i, j;
+
+ /*
+ * Look for a PMBR
+ */
+ if (readsects(&d, sector, 1, buf, 1) != 0)
+ return 0;
+
+ pmbr = (struct mbr_sector *)buf;
+
+ if (pmbr->mbr_magic != htole16(MBR_MAGIC))
+ return 0;
+
+ if (pmbr->mbr_parts[0].mbrp_type != MBR_PTYPE_PMBR)
+ return 0;
+
+ sector++; /* skip PMBR */
+
+ /*
+ * Look for a GPT header
+ * Space is scarce, we do not check CRC.
+ */
+ if (readsects(&d, sector, 1, buf, 1) != 0)
+ return 0;
+
+ hdr = (struct gpt_hdr *)buf;
+
+ if (memcmp(gpt_hdr_sig, hdr->hdr_sig, sizeof(hdr->hdr_sig)) != 0)
+ return 0;
+
+ if (hdr->hdr_revision != htole32(GPT_HDR_REVISION))
+ return 0;
+
+ if (le32toh(hdr->hdr_size) > DEV_BSIZE)
+ return 0;
+
+ nents = le32toh(hdr->hdr_entries);
+ entsz = le32toh(hdr->hdr_entsz);
+
+ sector++; /* skip GPT header */
+
+ /*
+ * Read partition table
+ *
+ * According to UEFI specification, entries are 128 * (2^n)
+ * bytes long. The most common scenario is 128 bytes (n = 0)
+ * where there are 4 entries per sector. If n > 2, then entries
+ * spans multiple sectors, but they remain sector-aligned.
+ */
+ entries_per_sector = DEV_BSIZE / entsz;
+ if (entries_per_sector == 0)
+ entries_per_sector = 1;
+
+ sectors_per_entry = entsz / DEV_BSIZE;
+ if (sectors_per_entry == 0)
+ sectors_per_entry = 1;
+
+ for (i = 0; i < nents; i += entries_per_sector) {
+ if (readsects(&d, sector, 1, buf, 1) != 0)
+ return 0;
+
+ sector += sectors_per_entry;
+
+ for (j = 0; j < entries_per_sector; j++) {
+ ent = (struct gpt_ent *)&buf[j * entsz];
+
+ if (is_unused(ent))
+ continue;
+
+ /* First bootme wins, we can stop there */
+ if (ent->ent_attr & GPT_ENT_ATTR_BOOTME) {
+ bootme_lba = le64toh(ent->ent_lba_start);
+ goto out;
+ }
+
+ if (firstpart_lba == 0)
+ firstpart_lba = le64toh(ent->ent_lba_start);
+
+ if (is_bootable(ent) && bootable_lba == 0)
+ bootable_lba = le64toh(ent->ent_lba_start);
+ }
+ }
+
+out:
+ if (bootme_lba)
+ return bootme_lba;
+
+ if (bootable_lba)
+ return bootable_lba;
+
+ if (firstpart_lba)
+ return firstpart_lba;
+
+ return 0;
+}
--
Emmanuel Dreyfus
m...@netbsd.org
