diff options
Diffstat (limited to 'contrib/syslinux-4.02/com32/lib/syslinux/memscan.c')
| -rw-r--r-- | contrib/syslinux-4.02/com32/lib/syslinux/memscan.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/com32/lib/syslinux/memscan.c b/contrib/syslinux-4.02/com32/lib/syslinux/memscan.c new file mode 100644 index 0000000..fc676cb --- /dev/null +++ b/contrib/syslinux-4.02/com32/lib/syslinux/memscan.c @@ -0,0 +1,158 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2007-2009 H. Peter Anvin - All Rights Reserved + * Copyright 2009 H. Peter Anvin - All Rights Reserved + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, + * copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom + * the Software is furnished to do so, subject to the following + * conditions: + * + * The above copyright notice and this permission notice shall + * be included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + * ----------------------------------------------------------------------- */ + +/* + * memscan.c + * + * Query the system for free memory + */ + +#include <assert.h> +#include <stdbool.h> +#include <stdlib.h> +#include <string.h> +#include <inttypes.h> +#include <com32.h> + +#include <syslinux/memscan.h> + +struct e820_entry { + uint64_t start; + uint64_t len; + uint32_t type; +}; + +int syslinux_scan_memory(scan_memory_callback_t callback, void *data) +{ + static com32sys_t ireg; + com32sys_t oreg; + struct e820_entry *e820buf; + uint64_t start, len, maxlen; + int memfound = 0; + int rv; + addr_t dosmem; + const addr_t bios_data = 0x510; /* Amount to reserve for BIOS data */ + + /* Use INT 12h to get DOS memory */ + __intcall(0x12, &__com32_zero_regs, &oreg); + dosmem = oreg.eax.w[0] << 10; + if (dosmem < 32 * 1024 || dosmem > 640 * 1024) { + /* INT 12h reports nonsense... now what? */ + uint16_t ebda_seg = *(uint16_t *) 0x40e; + if (ebda_seg >= 0x8000 && ebda_seg < 0xa000) + dosmem = ebda_seg << 4; + else + dosmem = 640 * 1024; /* Hope for the best... */ + } + rv = callback(data, bios_data, dosmem - bios_data, true); + if (rv) + return rv; + + /* First try INT 15h AX=E820h */ + e820buf = lzalloc(sizeof *e820buf); + if (!e820buf) + return -1; + + ireg.eax.l = 0xe820; + ireg.edx.l = 0x534d4150; + ireg.ebx.l = 0; + ireg.ecx.l = sizeof(*e820buf); + ireg.es = SEG(e820buf); + ireg.edi.w[0] = OFFS(e820buf); + + do { + __intcall(0x15, &ireg, &oreg); + + if ((oreg.eflags.l & EFLAGS_CF) || + (oreg.eax.l != 0x534d4150) || (oreg.ecx.l < 20)) + break; + + start = e820buf->start; + len = e820buf->len; + + if (start < 0x100000000ULL) { + /* Don't rely on E820 being valid for low memory. Doing so + could mean stuff like overwriting the PXE stack even when + using "keeppxe", etc. */ + if (start < 0x100000ULL) { + if (len > 0x100000ULL - start) + len -= 0x100000ULL - start; + else + len = 0; + start = 0x100000ULL; + } + + maxlen = 0x100000000ULL - start; + if (len > maxlen) + len = maxlen; + + if (len) { + rv = callback(data, (addr_t) start, (addr_t) len, + e820buf->type == 1); + if (rv) + return rv; + memfound = 1; + } + } + + ireg.ebx.l = oreg.ebx.l; + } while (oreg.ebx.l); + + lfree(e820buf); + + if (memfound) + return 0; + + /* Next try INT 15h AX=E801h */ + ireg.eax.w[0] = 0xe801; + __intcall(0x15, &ireg, &oreg); + + if (!(oreg.eflags.l & EFLAGS_CF) && oreg.ecx.w[0]) { + rv = callback(data, (addr_t) 1 << 20, oreg.ecx.w[0] << 10, true); + if (rv) + return rv; + + if (oreg.edx.w[0]) { + rv = callback(data, (addr_t) 16 << 20, oreg.edx.w[0] << 16, true); + if (rv) + return rv; + } + + return 0; + } + + /* Finally try INT 15h AH=88h */ + ireg.eax.w[0] = 0x8800; + if (!(oreg.eflags.l & EFLAGS_CF) && oreg.eax.w[0]) { + rv = callback(data, (addr_t) 1 << 20, oreg.ecx.w[0] << 10, true); + if (rv) + return rv; + } + + return 0; +} |