[PATCH v2 11/11] efi_loader: add ACPI table dump EFI app
Heinrich Schuchardt
heinrich.schuchardt at canonical.com
Sun Jun 21 10:19:15 CEST 2026
Provide an EFI binary that can dump all ACPI tables to files
<table_name>.dat. These can then be further analyzed by decompiling
with iasl.
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
v2:
Check checksums.
Check both RSDT and XSDT if both exist.
---
lib/efi_loader/Makefile | 3 +-
lib/efi_loader/acpidump.c | 563 ++++++++++++++++++++++++++++++++++++++
2 files changed, 565 insertions(+), 1 deletion(-)
create mode 100644 lib/efi_loader/acpidump.c
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 94ad6721a70..b9a3433a0c5 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -16,6 +16,7 @@ CFLAGS_efi_boottime.o += \
apps-$(CONFIG_RISCV) += boothart
apps-$(CONFIG_BOOTEFI_HELLO_COMPILE) += helloworld
apps-$(CONFIG_GENERATE_SMBIOS_TABLE) += smbiosdump
+apps-$(CONFIG_GENERATE_ACPI_TABLE) += acpidump
apps-$(CONFIG_EFI_LOAD_FILE2_INITRD) += initrddump
ifeq ($(CONFIG_GENERATE_ACPI_TABLE),)
apps-y += dtbdump
@@ -103,7 +104,7 @@ $(foreach f,$(apps-y) $(efi-obj-y),\
$(eval CFLAGS_REMOVE_$(f).o := $(CFLAGS_NON_EFI)))
# Link efi_app_common.o into each dump app
-$(obj)/dbginfodump_efi.so $(obj)/dtbdump_efi.so \
+$(obj)/acpidump_efi.so $(obj)/dbginfodump_efi.so $(obj)/dtbdump_efi.so \
$(obj)/initrddump_efi.so $(obj)/smbiosdump_efi.so: $(obj)/efi_app_common.o
always-y += $(foreach f,$(apps-y),$(f).efi)
diff --git a/lib/efi_loader/acpidump.c b/lib/efi_loader/acpidump.c
new file mode 100644
index 00000000000..3e5635fce5a
--- /dev/null
+++ b/lib/efi_loader/acpidump.c
@@ -0,0 +1,563 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2026, Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
+ *
+ * acpidump.efi saves the ACPI table set as file.
+ *
+ * Specifying 'nocolor' as load option data suppresses colored output and
+ * clearing of the screen.
+ */
+
+#include <efi_api.h>
+#include <part.h>
+#include <string.h>
+#include <acpi/acpi_table.h>
+#include "efi_app_common.h"
+
+#define MAX_FILENAME_LENGTH 32
+
+u16 app_banner[] = u"ACPI Dump\r\n=========\r\n\r\n";
+
+struct acpi_dump_table {
+ char signature[5];
+ uintptr_t addr;
+ u32 len;
+};
+
+static const efi_guid_t acpi2_guid = EFI_ACPI_TABLE_GUID;
+static const efi_guid_t acpi1_guid = EFI_GUID_EFI_ACPI1;
+
+/**
+ * checksum_ok() - check if byte-sum of buffer is zero
+ *
+ * @buf: buffer to check
+ * @len: buffer length
+ * Return: true if checksum is valid
+ */
+static bool checksum_ok(const void *buf, efi_uintn_t len)
+{
+ const u8 *pos = buf;
+ u8 sum = 0;
+
+ for (; len; --len, ++pos)
+ sum += *pos;
+
+ return !sum;
+}
+
+/**
+ * read_u32() - read 32-bit value via memcpy
+ *
+ * @src: source address
+ * Return: value
+ */
+static u32 read_u32(const void *src)
+{
+ u32 val;
+
+ memcpy(&val, src, sizeof(val));
+
+ return val;
+}
+
+/**
+ * read_u64() - read 64-bit value via memcpy
+ *
+ * @src: source address
+ * Return: value
+ */
+static u64 read_u64(const void *src)
+{
+ u64 val;
+
+ memcpy(&val, src, sizeof(val));
+
+ return val;
+}
+
+/**
+ * is_filename_char() - check if a signature byte is filename-safe
+ *
+ * @ch: character to check
+ * Return: true if filename-safe
+ */
+static bool is_filename_char(char ch)
+{
+ return (ch >= 'A' && ch <= 'Z') ||
+ (ch >= 'a' && ch <= 'z') ||
+ (ch >= '0' && ch <= '9') || ch == '_';
+}
+
+/**
+ * append_uint_dec() - append decimal representation of integer to UTF-16 string
+ *
+ * @str: destination UTF-16 string
+ * @pos: current write position
+ * @size: destination size in UTF-16 code units
+ * @val: value to append
+ * Return: updated write position
+ */
+static efi_uintn_t append_uint_dec(u16 *str, efi_uintn_t pos,
+ efi_uintn_t size, u32 val)
+{
+ u16 tmp[11];
+ efi_uintn_t n = 0;
+ efi_uintn_t i;
+
+ if (!val)
+ tmp[n++] = u'0';
+ while (val && n < ARRAY_SIZE(tmp)) {
+ tmp[n++] = u'0' + val % 10;
+ val /= 10;
+ }
+
+ for (i = 0; i < n && pos + 1 < size; ++i)
+ str[pos++] = tmp[n - i - 1];
+
+ if (pos < size)
+ str[pos] = 0;
+
+ return pos;
+}
+
+/**
+ * u32_to_utf16_dec() - convert unsigned integer to UTF-16 decimal string
+ *
+ * @dst: destination UTF-16 buffer
+ * @dst_size: destination size in UTF-16 code units
+ * @val: value to convert
+ */
+static void u32_to_utf16_dec(u16 *dst, efi_uintn_t dst_size, u32 val)
+{
+ append_uint_dec(dst, 0, dst_size, val);
+}
+
+/**
+ * build_table_filename() - construct table filename
+ *
+ * @sig: 4-byte ACPI signature string
+ * @instance: duplicate instance number (0 for first)
+ * @name: output filename buffer (UTF-16)
+ * @name_size: output filename buffer size in UTF-16 code units
+ */
+static void build_table_filename(const char *sig, u32 instance, u16 *name,
+ efi_uintn_t name_size)
+{
+ efi_uintn_t pos = 0;
+ int i;
+
+ if (!name_size)
+ return;
+
+ for (i = 0; i < 4 && pos + 1 < name_size; ++i)
+ name[pos++] = is_filename_char(sig[i]) ? (u16)sig[i] : u'_';
+
+ if (instance)
+ pos = append_uint_dec(name, pos, name_size, instance);
+
+ if (pos + 4 < name_size) {
+ name[pos++] = u'.';
+ name[pos++] = u'd';
+ name[pos++] = u'a';
+ name[pos++] = u't';
+ }
+ name[pos] = 0;
+}
+
+/**
+ * get_acpi_rsdp_addr() - find ACPI RSDP via EFI config table GUID
+ *
+ * Return: pointer to RSDP or NULL
+ */
+static struct acpi_rsdp *get_acpi_rsdp_addr(void)
+{
+ struct acpi_rsdp *rsdp;
+
+ rsdp = get_config_table(&acpi2_guid);
+ if (rsdp)
+ return rsdp;
+
+ rsdp = get_config_table(&acpi1_guid);
+
+ return rsdp;
+}
+
+/**
+ * add_table() - append one ACPI table entry
+ *
+ * @tables: table array
+ * @table_count: current table count
+ * @addr: table address
+ * @len: table length
+ * @sig: 4-character ACPI signature
+ * Return: status code
+ */
+static efi_status_t add_table(struct acpi_dump_table *tables, u32 *table_count,
+ uintptr_t addr, u32 len, const char *sig)
+{
+ struct acpi_dump_table *table = &tables[*table_count];
+
+ memset(table, 0, sizeof(*table));
+ memcpy(table->signature, sig, 4);
+ table->addr = addr;
+ table->len = len;
+ ++*table_count;
+
+ return EFI_SUCCESS;
+}
+
+/**
+ * has_table_addr() - check if a table address is already in the list
+ *
+ * @tables: table array
+ * @table_count: number of used entries
+ * @addr: table address to search
+ * Return: true if found
+ */
+static bool has_table_addr(struct acpi_dump_table *tables, u32 table_count,
+ uintptr_t addr)
+{
+ u32 i;
+
+ for (i = 0; i < table_count; ++i) {
+ if (tables[i].addr == addr)
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * collect_tables() - parse ACPI table structure and collect ACPI tables
+ *
+ * @tablesp: output table array
+ * @table_count: output table count
+ * Return: status code
+ */
+static efi_status_t collect_tables(struct acpi_dump_table **tablesp,
+ u32 *table_count)
+{
+ struct acpi_rsdp *rsdp;
+ struct acpi_table_header *root;
+ struct acpi_dump_table *tables;
+ uintptr_t root_addr;
+ u32 rsdp_len, root_len, max_tables;
+ u32 i, entries, entry_size;
+ bool use_xsdt;
+ efi_status_t ret;
+
+ rsdp = get_acpi_rsdp_addr();
+ if (!rsdp) {
+ error(u"No ACPI configuration table\r\n");
+ return EFI_NOT_FOUND;
+ }
+ print(u"RSDP address: 0x");
+ printx((uintptr_t)rsdp, 2 * sizeof(void *));
+ print(u"\r\n");
+
+ if (memcmp(rsdp->signature, RSDP_SIG, sizeof(rsdp->signature))) {
+ error(u"Invalid RSDP signature\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ if (!checksum_ok(rsdp, 20)) {
+ error(u"Invalid RSDP checksum\r\n");
+ return EFI_LOAD_ERROR;
+ }
+
+ rsdp_len = rsdp->revision >= ACPI_RSDP_REV_ACPI_2_0 ?
+ read_u32(&rsdp->length) : 20;
+ if (rsdp_len < 20) {
+ error(u"Invalid RSDP length\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ if (rsdp->revision >= ACPI_RSDP_REV_ACPI_2_0) {
+ if (rsdp_len < sizeof(struct acpi_rsdp)) {
+ error(u"Invalid ACPI 2.0 RSDP length\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ if (!checksum_ok(rsdp, rsdp_len)) {
+ error(u"Invalid ACPI 2.0 RSDP checksum\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ }
+
+ if (rsdp->revision >= ACPI_RSDP_REV_ACPI_2_0 &&
+ read_u64(&rsdp->xsdt_address)) {
+ root_addr = read_u64(&rsdp->xsdt_address);
+ use_xsdt = true;
+ } else {
+ root_addr = read_u32(&rsdp->rsdt_address);
+ use_xsdt = false;
+ }
+
+ if (!root_addr) {
+ error(u"Invalid RSDT/XSDT address\r\n");
+ return EFI_LOAD_ERROR;
+ }
+
+ root = (struct acpi_table_header *)root_addr;
+ root_len = read_u32(&root->length);
+ if (root_len < sizeof(*root)) {
+ error(u"Invalid RSDT/XSDT length\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ if (use_xsdt && memcmp(root->signature, "XSDT", 4)) {
+ error(u"Invalid XSDT signature\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ if (!use_xsdt && memcmp(root->signature, "RSDT", 4)) {
+ error(u"Invalid RSDT signature\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ if (!checksum_ok(root, root_len)) {
+ error(u"Invalid RSDT/XSDT checksum\r\n");
+ return EFI_LOAD_ERROR;
+ }
+
+ entry_size = use_xsdt ? sizeof(u64) : sizeof(u32);
+ if ((root_len - sizeof(*root)) % entry_size) {
+ error(u"Invalid RSDT/XSDT entry list\r\n");
+ return EFI_LOAD_ERROR;
+ }
+ entries = (root_len - sizeof(*root)) / entry_size;
+ /* RSDP + root + each root entry + up to DSDT/FACS per entry */
+ max_tables = 2 + 3 * entries;
+
+ ret = bs->allocate_pool(EFI_LOADER_DATA,
+ max_tables * sizeof(struct acpi_dump_table),
+ (void **)&tables);
+ if (ret != EFI_SUCCESS) {
+ error(u"Out of memory\r\n");
+ return ret;
+ }
+ *table_count = 0;
+
+ ret = add_table(tables, table_count, (uintptr_t)rsdp, rsdp_len, "RSDP");
+ if (ret != EFI_SUCCESS)
+ goto err_out;
+
+ ret = add_table(tables, table_count, root_addr, root_len, root->signature);
+ if (ret != EFI_SUCCESS)
+ goto err_out;
+
+ for (i = 0; i < entries; ++i) {
+ uintptr_t addr;
+ struct acpi_table_header *table;
+ u32 len;
+
+ if (use_xsdt) {
+ u64 *entry = (u64 *)((u8 *)root + sizeof(*root));
+
+ addr = read_u64(&entry[i]);
+ } else {
+ u32 *entry = (u32 *)((u8 *)root + sizeof(*root));
+
+ addr = read_u32(&entry[i]);
+ }
+ if (!addr)
+ continue;
+ if (has_table_addr(tables, *table_count, addr))
+ continue;
+
+ table = (struct acpi_table_header *)addr;
+ len = read_u32(&table->length);
+ if (len < sizeof(*table)) {
+ error(u"Invalid ACPI table length\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+ if (!checksum_ok(table, len)) {
+ error(u"Invalid ACPI table checksum\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+
+ ret = add_table(tables, table_count, addr, len, table->signature);
+ if (ret != EFI_SUCCESS)
+ goto err_out;
+
+ /*
+ * FADT (signature FACP) references DSDT and FACS outside RSDT/XSDT.
+ * Include them so output matches acpidump -b style completeness.
+ */
+ if (!memcmp(table->signature, "FACP", 4)) {
+ struct acpi_fadt *fadt = (struct acpi_fadt *)table;
+ uintptr_t dsdt_addr;
+ uintptr_t facs_addr;
+
+ if (len >= offsetof(struct acpi_fadt, x_dsdt) +
+ sizeof(fadt->x_dsdt))
+ dsdt_addr = read_u64(&fadt->x_dsdt);
+ else
+ dsdt_addr = 0;
+ if (!dsdt_addr)
+ dsdt_addr = read_u32(&fadt->dsdt);
+ if (dsdt_addr && !has_table_addr(tables, *table_count,
+ dsdt_addr)) {
+ struct acpi_table_header *dsdt;
+ u32 dsdt_len;
+
+ dsdt = (struct acpi_table_header *)dsdt_addr;
+ if (memcmp(dsdt->signature, "DSDT", 4)) {
+ error(u"Invalid DSDT signature\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+ dsdt_len = read_u32(&dsdt->length);
+ if (dsdt_len < sizeof(*dsdt)) {
+ error(u"Invalid DSDT length\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+ if (!checksum_ok(dsdt, dsdt_len)) {
+ error(u"Invalid DSDT checksum\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+
+ ret = add_table(tables, table_count, dsdt_addr, dsdt_len,
+ dsdt->signature);
+ if (ret != EFI_SUCCESS)
+ goto err_out;
+ }
+
+ if (len >= offsetof(struct acpi_fadt, x_firmware_ctrl) +
+ sizeof(fadt->x_firmware_ctrl))
+ facs_addr = read_u64(&fadt->x_firmware_ctrl);
+ else
+ facs_addr = 0;
+ if (!facs_addr)
+ facs_addr = read_u32(&fadt->firmware_ctrl);
+ if (facs_addr && !has_table_addr(tables, *table_count,
+ facs_addr)) {
+ struct acpi_facs *facs;
+ u32 facs_len;
+
+ facs = (struct acpi_facs *)facs_addr;
+ if (memcmp(facs->signature, "FACS", 4)) {
+ error(u"Invalid FACS signature\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+ facs_len = read_u32(&facs->length);
+ if (facs_len < sizeof(*facs)) {
+ error(u"Invalid FACS length\r\n");
+ ret = EFI_LOAD_ERROR;
+ goto err_out;
+ }
+ ret = add_table(tables, table_count, facs_addr, facs_len,
+ facs->signature);
+ if (ret != EFI_SUCCESS)
+ goto err_out;
+ }
+ }
+ }
+
+ *tablesp = tables;
+
+ return EFI_SUCCESS;
+
+err_out:
+ bs->free_pool(tables);
+ return ret;
+}
+
+/**
+ * do_check() - parse ACPI tables and report success/failure
+ *
+ * @args: unused command arguments
+ */
+static void do_check(u16 * __maybe_unused args)
+{
+ struct acpi_dump_table *tables;
+ u32 table_count;
+ u16 num[11] = {0};
+ efi_status_t ret;
+
+ ret = collect_tables(&tables, &table_count);
+ if (ret != EFI_SUCCESS)
+ return;
+
+ u32_to_utf16_dec(num, ARRAY_SIZE(num), table_count);
+
+ print(u"ACPI tables found: ");
+ print(num);
+ print(u"\r\n");
+
+ bs->free_pool(tables);
+ print(u"OK\r\n");
+}
+
+/**
+ * do_write() - ask filename and save ACPI table set
+ *
+ * @args: unused command arguments
+ */
+static void do_write(u16 * __maybe_unused args)
+{
+ struct acpi_dump_table *tables;
+ u16 filename[MAX_FILENAME_LENGTH];
+ u32 table_count;
+ u32 i;
+ efi_status_t ret;
+
+ ret = collect_tables(&tables, &table_count);
+ if (ret != EFI_SUCCESS)
+ return;
+ if (!table_count) {
+ print(u"No ACPI tables found\r\n");
+ bs->free_pool(tables);
+ return;
+ }
+
+ for (i = 0; i < table_count; ++i) {
+ u8 *buf;
+ u32 instance = 0;
+ u32 same_type = 0;
+ u32 j;
+
+ for (j = 0; j < table_count; ++j) {
+ if (!memcmp(tables[i].signature, tables[j].signature, 4))
+ ++same_type;
+ }
+
+ if (same_type > 1) {
+ /* Number duplicates starting at 1 for the first instance. */
+ for (j = 0; j <= i; ++j) {
+ if (!memcmp(tables[i].signature, tables[j].signature, 4))
+ ++instance;
+ }
+ }
+
+ build_table_filename(tables[i].signature, instance, filename,
+ ARRAY_SIZE(filename));
+
+ ret = bs->allocate_pool(EFI_LOADER_DATA, tables[i].len,
+ (void **)&buf);
+ if (ret != EFI_SUCCESS) {
+ error(u"Out of memory\r\n");
+ break;
+ }
+
+ memcpy(buf, (void *)tables[i].addr, tables[i].len);
+ ret = save_file(filename, buf, tables[i].len);
+ if (ret == EFI_SUCCESS) {
+ print(filename);
+ print(u" written\r\n");
+ }
+
+ bs->free_pool(buf);
+ if (ret == EFI_ACCESS_DENIED)
+ continue;
+ if (ret != EFI_SUCCESS)
+ break;
+ }
+
+ bs->free_pool(tables);
+}
+
+struct efi_app_cmd app_cmds[] = {
+ { u"check", u"check - parse ACPI table list\r\n", do_check },
+ { u"write", u"write - save one file per ACPI table\r\n", do_write },
+ { }
+};
--
2.53.0
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