From aea60a13b9d43bb4c5748a1216af954a0e9d22d4 Mon Sep 17 00:00:00 2001 From: Sam Eiderman Date: Wed, 16 Oct 2019 19:41:44 +0300 Subject: bootdevice: FW_CFG interface for LCHS values MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Using fw_cfg, supply logical CHS values directly from QEMU to the BIOS. Non-standard logical geometries break under QEMU. A virtual disk which contains an operating system which depends on logical geometries (consistent values being reported from BIOS INT13 AH=08) will most likely break under QEMU/SeaBIOS if it has non-standard logical geometries - for example 56 SPT (sectors per track). No matter what QEMU will report - SeaBIOS, for large enough disks - will use LBA translation, which will report 63 SPT instead. In addition we cannot force SeaBIOS to rely on physical geometries at all. A virtio-blk-pci virtual disk with 255 phyiscal heads cannot report more than 16 physical heads when moved to an IDE controller, since the ATA spec allows a maximum of 16 heads - this is an artifact of virtualization. By supplying the logical geometries directly we are able to support such "exotic" disks. We serialize this information in a similar way to the "bootorder" interface. The new fw_cfg entry is "bios-geometry". Reviewed-by: Karl Heubaum Reviewed-by: Arbel Moshe Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Sam Eiderman Signed-off-by: Sam Eiderman Tested-by: Philippe Mathieu-Daudé Signed-off-by: John Snow --- bootdevice.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'bootdevice.c') diff --git a/bootdevice.c b/bootdevice.c index 2cf6b37..03aaffc 100644 --- a/bootdevice.c +++ b/bootdevice.c @@ -405,3 +405,34 @@ void del_boot_device_lchs(DeviceState *dev, const char *suffix) } } } + +char *get_boot_devices_lchs_list(size_t *size) +{ + FWLCHSEntry *i; + size_t total = 0; + char *list = NULL; + + QTAILQ_FOREACH(i, &fw_lchs, link) { + char *bootpath; + char *chs_string; + size_t len; + + bootpath = get_boot_device_path(i->dev, false, i->suffix); + chs_string = g_strdup_printf("%s %" PRIu32 " %" PRIu32 " %" PRIu32, + bootpath, i->lcyls, i->lheads, i->lsecs); + + if (total) { + list[total - 1] = '\n'; + } + len = strlen(chs_string) + 1; + list = g_realloc(list, total + len); + memcpy(&list[total], chs_string, len); + total += len; + g_free(chs_string); + g_free(bootpath); + } + + *size = total; + + return list; +} -- cgit v1.1