From 2cbda736cea8f82cfc5caab0f6099f0fbfe28537 Mon Sep 17 00:00:00 2001 From: Warner Losh Date: Tue, 15 Oct 2024 18:03:03 -0600 Subject: [PATCH] gpart: Add warning when the start sector is too low. Add a warning if the starting sector is too low. The standard requires that at least 16k is reserved for the GPT Partition Array, but some tools produce GPT images with fewer than the required number of reserved sectors. PR: 274312 Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D42247 --- sys/geom/part/g_part_gpt.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/sys/geom/part/g_part_gpt.c b/sys/geom/part/g_part_gpt.c index 022337bd657..4733631c4b2 100644 --- a/sys/geom/part/g_part_gpt.c +++ b/sys/geom/part/g_part_gpt.c @@ -1045,6 +1045,20 @@ g_part_gpt_read(struct g_part_table *basetable, struct g_consumer *cp) g_free(sectbl); } + /* + * The reserved area preceeds the valid area for partitions. Warn when + * the lba_start doesn't meet the standard's minimum size for the gpt + * entry array. UEFI 2.10 section 5.3 specifies that the LBA must be 32 + * (for 512 byte sectors) or 6 (4k sectors) or larger. This is different + * than the number of valid entries in the GPT entry array, which can be + * smaller. + */ + if (table->hdr->hdr_lba_start < GPT_MIN_RESERVED / pp->sectorsize + 2) { + printf("GEOM: warning: %s lba_start %llu < required min %d\n", + pp->name, (unsigned long long)table->hdr->hdr_lba_start, + GPT_MIN_RESERVED / pp->sectorsize + 2); + } + basetable->gpt_first = table->hdr->hdr_lba_start; basetable->gpt_last = table->hdr->hdr_lba_end; basetable->gpt_entries = table->hdr->hdr_entries;