/*-
 * Copyright (c) 2005-2009 Jung-uk Kim <jkim@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stand.h>
#include <sys/endian.h>

#define PTOV(x)         ptov(x)

/*
 * Detect SMBIOS and export information about the SMBIOS into the
 * environment.
 *
 * System Management BIOS Reference Specification, v2.6 Final
 * http://www.dmtf.org/standards/published_documents/DSP0134_2.6.0.pdf
 *
 * System Management BIOS (SMBIOS) Reference Specification, 3.6.0
 * https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
 */

/*
 * The first quoted paragraph below can also be found in section 2.1.1 SMBIOS
 * Structure Table Entry Point of System Management BIOS Reference
 * Specification, v2.6 Final
 *
 * (From System Management BIOS (SMBIOS) Reference Specification, 3.6.0)
 * 5.2.1 SMBIOS 2.1 (32-bit) Entry Point
 *
 * "On non-UEFI systems, the 32-bit SMBIOS Entry Point structure, can be
 * located by application software by searching for the anchor-string on
 * paragraph (16-byte) boundaries within the physical memory address
 * range 000F0000h to 000FFFFFh. This entry point encapsulates an intermediate
 * anchor string that is used by some existing DMI browsers.
 *
 * On UEFI-based systems, the SMBIOS Entry Point structure can be located by
 * looking in the EFI Configuration Table for the SMBIOS GUID
 * (SMBIOS_TABLE_GUID, {EB9D2D31-2D88-11D3-9A16-0090273FC14D}) and using the
 * associated pointer. See section 4.6 of the UEFI Specification for details.
 * See section 2.3 of the UEFI Specification for how to report the containing
 * memory type.
 *
 * NOTE While the SMBIOS Major and Minor Versions (offsets 06h and 07h)
 * currently duplicate the information that is present in the SMBIOS BCD
 * Revision (offset 1Eh), they provide a path for future growth in this
 * specification. The BCD Revision, for example, provides only a single digit
 * for each of the major and minor version numbers."
 *
 * 5.2.2 SMBIOS 860 3.0 (64-bit) Entry Point
 *
 * "On non-UEFI systems, the 64-bit SMBIOS Entry Point structure can be located
 * by application software by searching for the anchor-string on paragraph
 * (16-byte) boundaries within the physical memory address range 000F0000h to
 * 000FFFFFh.
 *
 * On UEFI-based systems, the SMBIOS Entry Point structure can be located by
 * looking in the EFI Configuration Table for the SMBIOS 3.x GUID
 * (SMBIOS3_TABLE_GUID, {F2FD1544-9794-4A2C-992E-E5BBCF20E394}) and using the
 * associated pointer. See section 4.6 of the UEFI Specification for details.
 * See section 2.3 of the UEFI Specification for how to report the containing
 * memory type."
 */
#define SMBIOS_START            0xf0000
#define SMBIOS_LENGTH           0x10000
#define SMBIOS_STEP             0x10
#define SMBIOS_SIG              "_SM_"
#define SMBIOS3_SIG             "_SM3_"
#define SMBIOS_DMI_SIG          "_DMI_"
#define SMBIOS_EOT_TYPE         0x7f

/*
 * 5.1 General
 *...
 * NOTE The Entry Point Structure and all SMBIOS structures assume a
 * little-endian ordering convention...
 * ...
 *
 * We use memcpy to avoid unaligned access to memory. To normal memory, this is
 * fine, but the memory we are using might be mmap'd /dev/mem which under Linux
 * on aarch64 doesn't allow unaligned access. leXdec and friends can't be used
 * because those can optimize to an unaligned load (which often is fine, but not
 * for mmap'd /dev/mem which has special memory attributes).
 */
static inline uint8_t
SMBIOS_GET8(const caddr_t base, int off)
{
        return (base[off]);
}

static inline uint16_t
SMBIOS_GET16(const caddr_t base, int off)
{
        uint16_t v;

        memcpy(&v, base + off, sizeof(v));
        return (le16toh(v));
}

static inline uint32_t
SMBIOS_GET32(const caddr_t base, int off)
{
        uint32_t v;

        memcpy(&v, base + off, sizeof(v));
        return (le32toh(v));
}

static inline uint64_t
SMBIOS_GET64(const caddr_t base, int off)
{
        uint64_t v;

        memcpy(&v, base + off, sizeof(v));
        return (le64toh(v));
}

#define SMBIOS_GETLEN(base)     SMBIOS_GET8(base, 0x01)
#define SMBIOS_GETSTR(base)     ((base) + SMBIOS_GETLEN(base))

struct smbios_attr {
        int             is_64bit_ep;
        caddr_t         addr;
        size_t          length;
        size_t          count;
        int             major;
        int             minor;
        int             ver;
        const char*     bios_vendor;
        const char*     maker;
        const char*     product;
        uint32_t        enabled_memory;
        uint32_t        old_enabled_memory;
        uint8_t         enabled_sockets;
        uint8_t         populated_sockets;
};

static struct smbios_attr smbios;

static uint8_t
smbios_checksum(const caddr_t addr, const uint8_t len)
{
        uint8_t         sum;
        int             i;

        for (sum = 0, i = 0; i < len; i++)
                sum += SMBIOS_GET8(addr, i);
        return (sum);
}

static caddr_t
smbios_sigsearch(const caddr_t addr, const uint32_t len)
{
        caddr_t         cp;
        caddr_t         v2_p = NULL;

        /* Search on 16-byte boundaries. */
        for (cp = addr; cp < addr + len; cp += SMBIOS_STEP) {
                /* v3.0, 64-bit Entry point */
                if (strncmp(cp, SMBIOS3_SIG, sizeof(SMBIOS3_SIG) - 1) == 0 &&
                    /*
                     * The specification only guarantees the presence of the
                     * Structure Table Maximum Size and Address Entry fields at
                     * offsets 0x0c and 0x10 if the Entry Point Revision is not
                     * 0.
                     */
                    SMBIOS_GET8(cp, 0x0a) != 0 &&
                    smbios_checksum(cp, SMBIOS_GET8(cp, 0x06)) == 0) {
#if __SIZEOF_SIZE_T__ < 8
                        uint64_t end_addr;

                        end_addr = SMBIOS_GET64(cp, 0x10) + /* Start address. */
                            SMBIOS_GET32(cp, 0x0c); /* Maximum size. */
                        /*
                         * Is the table (or part of it) located above what we
                         * can address?
                         */
                        if ((size_t)end_addr != end_addr)
                                /* Yes, give it up. */
                                continue;
#endif
                        smbios.is_64bit_ep = 1;
                        return (cp);
                }

                /* v2.1, 32-bit Entry point */
                if (strncmp(cp, SMBIOS_SIG, sizeof(SMBIOS_SIG) - 1) == 0 &&
                    smbios_checksum(cp, SMBIOS_GET8(cp, 0x05)) == 0 &&
                    strncmp(cp + 0x10, SMBIOS_DMI_SIG, 5) == 0 &&
                    smbios_checksum(cp + 0x10, 0x0f) == 0) {
                        /*
                         * Note that we saw this entry point, but don't return
                         * it right now as we favor the 64-bit one if present.
                         */
                        v2_p = cp;
                }
        }
        return (v2_p);
}

static const char*
smbios_getstring(caddr_t addr, const int offset)
{
        caddr_t         cp;
        int             i, idx;

        idx = SMBIOS_GET8(addr, offset);
        if (idx != 0) {
                cp = SMBIOS_GETSTR(addr);
                for (i = 1; i < idx; i++)
                        cp += strlen(cp) + 1;
                return cp;
        }
        return (NULL);
}

static void
smbios_setenv(const char *name, caddr_t addr, const int offset)
{
        const char*     val;

        val = smbios_getstring(addr, offset);
        if (val != NULL)
                setenv(name, val, 1);
}

#ifdef SMBIOS_SERIAL_NUMBERS

#define UUID_SIZE               16
#define UUID_TYPE               uint32_t
#define UUID_STEP               sizeof(UUID_TYPE)
#define UUID_ALL_BITS           (UUID_SIZE / UUID_STEP)
#define UUID_GET(base, off)     SMBIOS_GET32(base, off)

static void
smbios_setuuid(const char *name, const caddr_t addr, const int ver __unused)
{
        char            uuid[37];
        int             byteorder, i, ones, zeros;
        UUID_TYPE       n;
        uint32_t        f1;
        uint16_t        f2, f3;

        for (i = 0, ones = 0, zeros = 0; i < UUID_SIZE; i += UUID_STEP) {
                n = UUID_GET(addr, i) + 1;
                if (zeros == 0 && n == 0)
                        ones++;
                else if (ones == 0 && n == 1)
                        zeros++;
                else
                        break;
        }

        if (ones != UUID_ALL_BITS && zeros != UUID_ALL_BITS) {
                /*
                 * 3.3.2.1 System UUID
                 *
                 * "Although RFC 4122 recommends network byte order for all
                 * fields, the PC industry (including the ACPI, UEFI, and
                 * Microsoft specifications) has consistently used
                 * little-endian byte encoding for the first three fields:
                 * time_low, time_mid, time_hi_and_version. The same encoding,
                 * also known as wire format, should also be used for the
                 * SMBIOS representation of the UUID."
                 *
                 * Note: We use network byte order for backward compatibility
                 * unless SMBIOS version is 2.6+ or little-endian is forced.
                 */
#if defined(SMBIOS_LITTLE_ENDIAN_UUID)
                byteorder = LITTLE_ENDIAN;
#elif defined(SMBIOS_NETWORK_ENDIAN_UUID)
                byteorder = BIG_ENDIAN;
#else
                byteorder = ver < 0x0206 ? BIG_ENDIAN : LITTLE_ENDIAN;
#endif
                if (byteorder != LITTLE_ENDIAN) {
                        f1 = ntohl(SMBIOS_GET32(addr, 0));
                        f2 = ntohs(SMBIOS_GET16(addr, 4));
                        f3 = ntohs(SMBIOS_GET16(addr, 6));
                } else {
                        f1 = le32toh(SMBIOS_GET32(addr, 0));
                        f2 = le16toh(SMBIOS_GET16(addr, 4));
                        f3 = le16toh(SMBIOS_GET16(addr, 6));
                }
                sprintf(uuid,
                    "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
                    f1, f2, f3, SMBIOS_GET8(addr, 8), SMBIOS_GET8(addr, 9),
                    SMBIOS_GET8(addr, 10), SMBIOS_GET8(addr, 11),
                    SMBIOS_GET8(addr, 12), SMBIOS_GET8(addr, 13),
                    SMBIOS_GET8(addr, 14), SMBIOS_GET8(addr, 15));
                setenv(name, uuid, 1);
        }
}

#undef UUID_SIZE
#undef UUID_TYPE
#undef UUID_STEP
#undef UUID_ALL_BITS
#undef UUID_GET

#endif

static const char *
smbios_parse_chassis_type(caddr_t addr)
{
        int             type;

        type = SMBIOS_GET8(addr, 0x5);
        switch (type) {
        case 0x1:
                return ("Other");
        case 0x2:
                return ("Unknown");
        case 0x3:
                return ("Desktop");
        case 0x4:
                return ("Low Profile Desktop");
        case 0x5:
                return ("Pizza Box");
        case 0x6:
                return ("Mini Tower");
        case 0x7:
                return ("Tower");
        case 0x8:
                return ("Portable");
        case 0x9:
                return ("Laptop");
        case 0xA:
                return ("Notebook");
        case 0xB:
                return ("Hand Held");
        case 0xC:
                return ("Docking Station");
        case 0xD:
                return ("All in One");
        case 0xE:
                return ("Sub Notebook");
        case 0xF:
                return ("Lunch Box");
        case 0x10:
                return ("Space-saving");
        case 0x11:
                return ("Main Server Chassis");
        case 0x12:
                return ("Expansion Chassis");
        case 0x13:
                return ("SubChassis");
        case 0x14:
                return ("Bus Expansion Chassis");
        case 0x15:
                return ("Peripheral Chassis");
        case 0x16:
                return ("RAID Chassis");
        case 0x17:
                return ("Rack Mount Chassis");
        case 0x18:
                return ("Sealed-case PC");
        case 0x19:
                return ("Multi-system chassis");
        case 0x1A:
                return ("Compact PCI");
        case 0x1B:
                return ("Advanced TCA");
        case 0x1C:
                return ("Blade");
        case 0x1D:
                return ("Blade Enclosure");
        case 0x1E:
                return ("Tablet");
        case 0x1F:
                return ("Convertible");
        case 0x20:
                return ("Detachable");
        case 0x21:
                return ("IoT Gateway");
        case 0x22:
                return ("Embedded PC");
        case 0x23:
                return ("Mini PC");
        case 0x24:
                return ("Stick PC");
        }

        return ("Undefined");
}

static caddr_t
smbios_parse_table(const caddr_t addr)
{
        caddr_t         cp;
        int             proc, size, osize, type;
        uint8_t         bios_minor, bios_major;
        char            buf[16];

        type = SMBIOS_GET8(addr, 0);    /* 3.1.2 Structure Header Format */
        switch(type) {
        case 0:         /* 3.3.1 BIOS Information (Type 0) */
                smbios_setenv("smbios.bios.vendor", addr, 0x04);
                smbios_setenv("smbios.bios.version", addr, 0x05);
                smbios_setenv("smbios.bios.reldate", addr, 0x08);
                bios_major = SMBIOS_GET8(addr, 0x14);
                bios_minor = SMBIOS_GET8(addr, 0x15);
                if (bios_minor != 0xFF && bios_major != 0xFF) {
                        snprintf(buf, sizeof(buf), "%u.%u",
                            bios_major, bios_minor);
                        setenv("smbios.bios.revision", buf, 1);
                }
                break;

        case 1:         /* 3.3.2 System Information (Type 1) */
                smbios_setenv("smbios.system.maker", addr, 0x04);
                smbios_setenv("smbios.system.product", addr, 0x05);
                smbios_setenv("smbios.system.version", addr, 0x06);
#ifdef SMBIOS_SERIAL_NUMBERS
                smbios_setenv("smbios.system.serial", addr, 0x07);
                smbios_setuuid("smbios.system.uuid", addr + 0x08, smbios.ver);
#endif
                if (smbios.major > 2 ||
                    (smbios.major == 2 && smbios.minor >= 4)) {
                        smbios_setenv("smbios.system.sku", addr, 0x19);
                        smbios_setenv("smbios.system.family", addr, 0x1a);
                }
                break;

        case 2:         /* 3.3.3 Base Board (or Module) Information (Type 2) */
                smbios_setenv("smbios.planar.maker", addr, 0x04);
                smbios_setenv("smbios.planar.product", addr, 0x05);
                smbios_setenv("smbios.planar.version", addr, 0x06);
#ifdef SMBIOS_SERIAL_NUMBERS
                smbios_setenv("smbios.planar.serial", addr, 0x07);
                smbios_setenv("smbios.planar.tag", addr, 0x08);
#endif
                smbios_setenv("smbios.planar.location", addr, 0x0a);
                break;

        case 3:         /* 3.3.4 System Enclosure or Chassis (Type 3) */
                smbios_setenv("smbios.chassis.maker", addr, 0x04);
                setenv("smbios.chassis.type", smbios_parse_chassis_type(addr), 1);
                smbios_setenv("smbios.chassis.version", addr, 0x06);
#ifdef SMBIOS_SERIAL_NUMBERS
                smbios_setenv("smbios.chassis.serial", addr, 0x07);
                smbios_setenv("smbios.chassis.tag", addr, 0x08);
#endif
                break;

        case 4:         /* 3.3.5 Processor Information (Type 4) */
                smbios_setenv("smbios.processor.version", addr, 0x10);
                /*
                 * Offset 18h: Processor Status
                 *
                 * Bit 7        Reserved, must be 0
                 * Bit 6        CPU Socket Populated
                 *              1 - CPU Socket Populated
                 *              0 - CPU Socket Unpopulated
                 * Bit 5:3      Reserved, must be zero
                 * Bit 2:0      CPU Status
                 *              0h - Unknown
                 *              1h - CPU Enabled
                 *              2h - CPU Disabled by User via BIOS Setup
                 *              3h - CPU Disabled by BIOS (POST Error)
                 *              4h - CPU is Idle, waiting to be enabled
                 *              5-6h - Reserved
                 *              7h - Other
                 */
                proc = SMBIOS_GET8(addr, 0x18);
                if ((proc & 0x07) == 1)
                        smbios.enabled_sockets++;
                if ((proc & 0x40) != 0)
                        smbios.populated_sockets++;
                break;

        case 6:         /* 3.3.7 Memory Module Information (Type 6, Obsolete) */
                /*
                 * Offset 0Ah: Enabled Size
                 *
                 * Bit 7        Bank connection
                 *              1 - Double-bank connection
                 *              0 - Single-bank connection
                 * Bit 6:0      Size (n), where 2**n is the size in MB
                 *              7Dh - Not determinable (Installed Size only)
                 *              7Eh - Module is installed, but no memory
                 *                    has been enabled
                 *              7Fh - Not installed
                 */
                osize = SMBIOS_GET8(addr, 0x0a) & 0x7f;
                if (osize > 0 && osize < 22)
                        smbios.old_enabled_memory += 1 << (osize + 10);
                break;

        case 17:        /* 3.3.18 Memory Device (Type 17) */
                /*
                 * Offset 0Ch: Size
                 *
                 * Bit 15       Granularity
                 *              1 - Value is in kilobytes units
                 *              0 - Value is in megabytes units
                 * Bit 14:0     Size
                 */
                size = SMBIOS_GET16(addr, 0x0c);
                if (size != 0 && size != 0xffff)
                        smbios.enabled_memory += (size & 0x8000) != 0 ?
                            (size & 0x7fff) : (size << 10);
                break;

        case SMBIOS_EOT_TYPE:   /* 3.3.42 End-of-Table (Type 127) */
                return (NULL);

        default:        /* skip other types */
                break;
        }

        /* Find structure terminator. */
        cp = SMBIOS_GETSTR(addr);
        while (SMBIOS_GET16(cp, 0) != 0)
                cp++;

        return (cp + 2);
}

static caddr_t
smbios_find_struct(int type)
{
        caddr_t         dmi;
        size_t          i;
        caddr_t         ep;

        if (smbios.addr == NULL)
                return (NULL);

        ep = smbios.addr + smbios.length;
        for (dmi = smbios.addr, i = 0;
             dmi < ep && i < smbios.count; i++) {
                const uint8_t seen_type = SMBIOS_GET8(dmi, 0);

                if (seen_type == type)
                        return (dmi);
                if (seen_type == SMBIOS_EOT_TYPE)
                        /* End of table. */
                        break;
                /* Find structure terminator. */
                dmi = SMBIOS_GETSTR(dmi);
                while (SMBIOS_GET16(dmi, 0) != 0 && dmi < ep)
                        dmi++;
                /* Skip it. */
                dmi += 2;
        }

        return (NULL);
}

static void
smbios_probe(const caddr_t addr)
{
        caddr_t         saddr, info;
        uintptr_t       paddr;
        int             maj_off;
        int             min_off;

        /* Search signatures and validate checksums. */
        saddr = addr != NULL ? smbios_sigsearch(addr, 1) :
            smbios_sigsearch(PTOV(SMBIOS_START), SMBIOS_LENGTH);
        if (saddr == NULL)
                return;

        if (smbios.is_64bit_ep) {
                /* Structure Table Length */
                smbios.length = SMBIOS_GET32(saddr, 0x0c);
                /* Structure Table Address */
                paddr = SMBIOS_GET64(saddr, 0x10);
                /* Not present in V3, set it to the maximum value (no limit). */
                smbios.count = -1;
                /*
                 * No BCD revision in V3, we'll determine the version thanks to
                 * the major and minor fields below.
                 */
                smbios.ver = 0;
                maj_off = 0x07;
                min_off = 0x08;
        } else {
                /* Structure Table Length */
                smbios.length = SMBIOS_GET16(saddr, 0x16);
                /* Structure Table Address */
                paddr = SMBIOS_GET32(saddr, 0x18);
                /* No. of SMBIOS Structures */
                smbios.count = SMBIOS_GET16(saddr, 0x1c);
                /* SMBIOS BCD Revision */
                smbios.ver = SMBIOS_GET8(saddr, 0x1e);
                if (smbios.ver != 0) {
                        smbios.major = smbios.ver >> 4;
                        smbios.minor = smbios.ver & 0x0f;
                        if (smbios.major > 9 || smbios.minor > 9)
                                smbios.ver = 0;
                }
                maj_off = 0x06;
                min_off = 0x07;
        }


        if (smbios.ver == 0) {
                /*
                 * v3 table, or v2 with BCD revision being 0 or bad.  Use the
                 * major and minor version fields.
                 */
                smbios.major = SMBIOS_GET8(saddr, maj_off);
                smbios.minor = SMBIOS_GET8(saddr, min_off);
        }
        smbios.ver = (smbios.major << 8) | smbios.minor;
        smbios.addr = PTOV(paddr);

        /* Get system information from SMBIOS */
        info = smbios_find_struct(0x00);
        if (info != NULL) {
                smbios.bios_vendor = smbios_getstring(info, 0x04);
        }
        info = smbios_find_struct(0x01);
        if (info != NULL) {
                smbios.maker = smbios_getstring(info, 0x04);
                smbios.product = smbios_getstring(info, 0x05);
        }
}

caddr_t
smbios_detect(const caddr_t addr)
{
        char            buf[16];
        caddr_t         dmi;
        size_t          i;

        smbios_probe(addr);
        if (smbios.addr == NULL)
                return (NULL);

        for (dmi = smbios.addr, i = 0; dmi != NULL &&
            dmi < smbios.addr + smbios.length && i < smbios.count; i++)
                dmi = smbios_parse_table(dmi);

        setenv("smbios.entry_point_type", smbios.is_64bit_ep ?
            "v3 (64-bit)" : "v2.1 (32-bit)", 1);
        sprintf(buf, "%d.%d", smbios.major, smbios.minor);
        setenv("smbios.version", buf, 1);
        if (smbios.enabled_memory > 0 || smbios.old_enabled_memory > 0) {
                sprintf(buf, "%u", smbios.enabled_memory > 0 ?
                    smbios.enabled_memory : smbios.old_enabled_memory);
                setenv("smbios.memory.enabled", buf, 1);
        }
        if (smbios.enabled_sockets > 0) {
                sprintf(buf, "%u", smbios.enabled_sockets);
                setenv("smbios.socket.enabled", buf, 1);
        }
        if (smbios.populated_sockets > 0) {
                sprintf(buf, "%u", smbios.populated_sockets);
                setenv("smbios.socket.populated", buf, 1);
        }

        return (smbios.addr);
}

static int
smbios_match_str(const char* s1, const char* s2)
{
        return (s1 == NULL || (s2 != NULL && !strcmp(s1, s2)));
}

int
smbios_match(const char* bios_vendor, const char* maker,
    const char* product)
{
        static bool probed = false;

        /*
         * This routine is called only from non-EFI loaders on determining the
         * amount of usable memory.  In particular, it is so before malloc() can
         * be used, so before smbios_detect() can be called (as it uses
         * setenv()).  Consequently, since smbios_probe() is not exported, we
         * ensure it has been called beforehand to fetch into the static
         * 'smbios' structure the metadata that is to be matched.
         */
        if (!probed) {
                probed = true;
                smbios_probe(NULL);
        }

        return (smbios_match_str(bios_vendor, smbios.bios_vendor) &&
            smbios_match_str(maker, smbios.maker) &&
            smbios_match_str(product, smbios.product));
}