1 /* ----------------------------------------------------------------------- *
3 * Copyright 2010 Intel Corporation; author: H. Peter Anvin
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
8 * Boston MA 02110-1301, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
11 * ----------------------------------------------------------------------- */
16 * Simple utility to search for a MEMDISK instance and output the parameters
17 * needed to use the "phram" driver in Linux to map it.
30 #include "../memdisk/mstructs.h"
32 #define MBFT_MIN_LENGTH (36+4+26)
34 static bool valid_mbft(const struct mBFT *mbft, size_t space)
39 if (memcmp(mbft->acpi.signature, "mBFT", 4))
42 if (mbft->acpi.length < MBFT_MIN_LENGTH)
45 if (mbft->acpi.length > space)
48 if ((size_t)mbft->acpi.length != (size_t)mbft->mdi.bytes + 36+4)
52 for (i = 0; i < mbft->acpi.length; i++)
53 csum += ((const uint8_t *)mbft)[i];
61 static void output_params(const struct mBFT *mbft)
63 int sector_shift = mbft->mdi.sector_shift;
69 mbft->mdi.diskbuf, mbft->mdi.disksize << sector_shift);
72 static size_t memlimit(void)
74 char txtline[256], user[256];
76 unsigned long long start, end;
79 iomem = fopen("/proc/iomem", "r");
83 while (fgets(txtline, sizeof txtline, iomem) != NULL) {
84 if (sscanf(txtline, "%llx-%llx : %[^\n]", &start, &end, user) != 3)
86 if (strcmp(user, "System RAM"))
90 maxram = (end >= 0xa0000) ? 0xa0000 : end+1;
97 static inline size_t get_page_size(void)
100 return sysconf(_SC_PAGESIZE);
102 /* klibc, for one, doesn't have sysconf() due to excessive multiplex */
103 return getpagesize();
107 int main(int argc, char *argv[])
112 const char *ptr, *end;
113 size_t page = get_page_size();
114 size_t mapbase, maplen;
119 mapbase = memlimit() & ~(page - 1);
123 memfd = open("/dev/mem", O_RDONLY);
125 fprintf(stderr, "%s: cannot open /dev/mem: %s\n",
126 argv[0], strerror(errno));
130 map = mmap(NULL, page, PROT_READ, MAP_SHARED, memfd, 0);
131 if (map == MAP_FAILED) {
132 fprintf(stderr, "%s: cannot map page 0: %s\n",
133 argv[0], strerror(errno));
137 fbm = *(uint16_t *)(map + 0x413) << 10;
141 munmap((void *)map, page);
143 if (fbm < 64*1024 || fbm >= 640*1024)
146 maplen = 0xa0000 - mapbase;
147 map = mmap(NULL, maplen, PROT_READ, MAP_SHARED, memfd, mapbase);
148 if (map == MAP_FAILED) {
149 fprintf(stderr, "%s: cannot map base memory: %s\n",
150 argv[0], strerror(errno));
154 ptr = map + (fbm - mapbase);
155 end = map + (0xa0000 - mapbase);
157 if (valid_mbft((const struct mBFT *)ptr, end-ptr)) {
158 output_params((const struct mBFT *)ptr);
165 munmap((void *)map, maplen);