[PATCH v3 11/11] efi_loader: add ACPI table dump EFI app
Ilias Apalodimas
ilias.apalodimas at linaro.org
Thu Jul 2 10:48:18 CEST 2026
Heinrich,
Didn't I have a tested-by and acked-by tag on this?
Cheers
/Ilias
On Sun, 28 Jun 2026 at 11:28, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
> 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.
>
> The DSDT and FACS tables are identified via FADT.
>
> The following commands are provided:
>
> * check - parse ACPI table list\r\n", do_check
> * write - save one file per ACPI table\r\n", do_write
>
> The file names are constructed from:
>
> * 4 character ACPI table name
> * number if there are multiple ACPI tables of the same type
> * '.dat' extension
>
> This matches the output of the Linux `acpidump -b` command.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
> v3:
> extend the commit message
> reformat with clang-format
> roll in u32_to_utf16_dec()
> in add_tables() check against max_tables
> v2:
> Check checksums.
> Check both RSDT and XSDT if both exist.
> ---
> lib/efi_loader/Makefile | 3 +-
> lib/efi_loader/acpidump.c | 566 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 568 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..374d43d7a10
> --- /dev/null
> +++ b/lib/efi_loader/acpidump.c
> @@ -0,0 +1,566 @@
> +// 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;
> +}
> +
> +/**
> + * 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
> + * @max_tables: size of the table array
> + * @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,
> + u32 max_tables, uintptr_t addr, u32 len,
> + const char *sig)
> +{
> + struct acpi_dump_table *table = &tables[*table_count];
> +
> + if (*table_count >= max_tables) {
> + error(u"add_table: buffer too small\r\n");
> +
> + return EFI_BUFFER_TOO_SMALL;
> + }
> +
> + 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, max_tables, (uintptr_t)rsdp,
> + rsdp_len, "RSDP");
> + if (ret != EFI_SUCCESS)
> + goto err_out;
> +
> + ret = add_table(tables, table_count, max_tables, 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, max_tables, 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, max_tables,
> + 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, max_tables,
> + 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;
> +
> + append_uint_dec(num, 0, 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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