diff options
Diffstat (limited to 'src/hw/block/hd-geometry.c')
| -rw-r--r-- | src/hw/block/hd-geometry.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/src/hw/block/hd-geometry.c b/src/hw/block/hd-geometry.c new file mode 100644 index 0000000..b187878 --- /dev/null +++ b/src/hw/block/hd-geometry.c @@ -0,0 +1,165 @@ +/* + * Hard disk geometry utilities + * + * Copyright (C) 2012 Red Hat, Inc. + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + * + * This file incorporates work covered by the following copyright and + * permission notice: + * + * Copyright (c) 2003 Fabrice Bellard + * + * 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. + */ + +#include "sysemu/block-backend.h" +#include "hw/block/block.h" +#include "trace.h" + +struct partition { + uint8_t boot_ind; /* 0x80 - active */ + uint8_t head; /* starting head */ + uint8_t sector; /* starting sector */ + uint8_t cyl; /* starting cylinder */ + uint8_t sys_ind; /* What partition type */ + uint8_t end_head; /* end head */ + uint8_t end_sector; /* end sector */ + uint8_t end_cyl; /* end cylinder */ + uint32_t start_sect; /* starting sector counting from 0 */ + uint32_t nr_sects; /* nr of sectors in partition */ +} QEMU_PACKED; + +/* try to guess the disk logical geometry from the MSDOS partition table. + Return 0 if OK, -1 if could not guess */ +static int guess_disk_lchs(BlockBackend *blk, + int *pcylinders, int *pheads, int *psectors) +{ + uint8_t buf[BDRV_SECTOR_SIZE]; + int i, heads, sectors, cylinders; + struct partition *p; + uint32_t nr_sects; + uint64_t nb_sectors; + + blk_get_geometry(blk, &nb_sectors); + + /** + * The function will be invoked during startup not only in sync I/O mode, + * but also in async I/O mode. So the I/O throttling function has to + * be disabled temporarily here, not permanently. + */ + if (blk_read_unthrottled(blk, 0, buf, 1) < 0) { + return -1; + } + /* test msdos magic */ + if (buf[510] != 0x55 || buf[511] != 0xaa) { + return -1; + } + for (i = 0; i < 4; i++) { + p = ((struct partition *)(buf + 0x1be)) + i; + nr_sects = le32_to_cpu(p->nr_sects); + if (nr_sects && p->end_head) { + /* We make the assumption that the partition terminates on + a cylinder boundary */ + heads = p->end_head + 1; + sectors = p->end_sector & 63; + if (sectors == 0) { + continue; + } + cylinders = nb_sectors / (heads * sectors); + if (cylinders < 1 || cylinders > 16383) { + continue; + } + *pheads = heads; + *psectors = sectors; + *pcylinders = cylinders; + trace_hd_geometry_lchs_guess(blk, cylinders, heads, sectors); + return 0; + } + } + return -1; +} + +static void guess_chs_for_size(BlockBackend *blk, + uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs) +{ + uint64_t nb_sectors; + int cylinders; + + blk_get_geometry(blk, &nb_sectors); + + cylinders = nb_sectors / (16 * 63); + if (cylinders > 16383) { + cylinders = 16383; + } else if (cylinders < 2) { + cylinders = 2; + } + *pcyls = cylinders; + *pheads = 16; + *psecs = 63; +} + +void hd_geometry_guess(BlockBackend *blk, + uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs, + int *ptrans) +{ + int cylinders, heads, secs, translation; + HDGeometry geo; + + /* Try to probe the backing device geometry, otherwise fallback + to the old logic. (as of 12/2014 probing only succeeds on DASDs) */ + if (blk_probe_geometry(blk, &geo) == 0) { + *pcyls = geo.cylinders; + *psecs = geo.sectors; + *pheads = geo.heads; + translation = BIOS_ATA_TRANSLATION_NONE; + } else if (guess_disk_lchs(blk, &cylinders, &heads, &secs) < 0) { + /* no LCHS guess: use a standard physical disk geometry */ + guess_chs_for_size(blk, pcyls, pheads, psecs); + translation = hd_bios_chs_auto_trans(*pcyls, *pheads, *psecs); + } else if (heads > 16) { + /* LCHS guess with heads > 16 means that a BIOS LBA + translation was active, so a standard physical disk + geometry is OK */ + guess_chs_for_size(blk, pcyls, pheads, psecs); + translation = *pcyls * *pheads <= 131072 + ? BIOS_ATA_TRANSLATION_LARGE + : BIOS_ATA_TRANSLATION_LBA; + } else { + /* LCHS guess with heads <= 16: use as physical geometry */ + *pcyls = cylinders; + *pheads = heads; + *psecs = secs; + /* disable any translation to be in sync with + the logical geometry */ + translation = BIOS_ATA_TRANSLATION_NONE; + } + if (ptrans) { + *ptrans = translation; + } + trace_hd_geometry_guess(blk, *pcyls, *pheads, *psecs, translation); +} + +int hd_bios_chs_auto_trans(uint32_t cyls, uint32_t heads, uint32_t secs) +{ + return cyls <= 1024 && heads <= 16 && secs <= 63 + ? BIOS_ATA_TRANSLATION_NONE + : BIOS_ATA_TRANSLATION_LBA; +} |
