Hi Sam,
On 9/25/19 1:06 PM, Sam Eiderman wrote:
> From: Sam Eiderman <shmuel.eider...@oracle.com>
>
> 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 <karl.heub...@oracle.com>
> Reviewed-by: Arbel Moshe <arbel.mo...@oracle.com>
> Signed-off-by: Sam Eiderman <shmuel.eider...@oracle.com>
> ---
> bootdevice.c | 32 ++++++++++++++++++++++++++++++++
> hw/nvram/fw_cfg.c | 14 +++++++++++---
> include/sysemu/sysemu.h | 1 +
> 3 files changed, 44 insertions(+), 3 deletions(-)
>
> diff --git a/bootdevice.c b/bootdevice.c
> index 2b12fb85a4..b034ad7bdc 100644
> --- a/bootdevice.c
> +++ b/bootdevice.c
> @@ -405,3 +405,35 @@ void del_boot_device_lchs(DeviceState *dev, const char
> *suffix)
> }
> }
> }
> +
> +/* Serialized as: (device name\0 + lchs struct) x devices */
> +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);
Hmm maybe we can g_free(bootpath) directly here.
> +
> + 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;
> +}
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 7dc3ac378e..18aff658c0 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -920,13 +920,21 @@ void *fw_cfg_modify_file(FWCfgState *s, const char
> *filename,
>
> static void fw_cfg_machine_reset(void *opaque)
> {
> + MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
> + FWCfgState *s = opaque;
> void *ptr;
> size_t len;
> - FWCfgState *s = opaque;
> - char *bootindex = get_boot_devices_list(&len);
> + char *buf;
>
> - ptr = fw_cfg_modify_file(s, "bootorder", (uint8_t *)bootindex, len);
> + buf = get_boot_devices_list(&len);
> + ptr = fw_cfg_modify_file(s, "bootorder", (uint8_t *)buf, len);
> g_free(ptr);
> +
> + if (!mc->legacy_fw_cfg_order) {
> + buf = get_boot_devices_lchs_list(&len);
> + ptr = fw_cfg_modify_file(s, "bios-geometry", (uint8_t *)buf, len);
OK. Can you add a test in tests/fw_cfg-test.c please?
> + g_free(ptr);
> + }
> }
>
> static void fw_cfg_machine_ready(struct Notifier *n, void *data)
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index 5bc5c79cbc..80c57fdc4e 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -106,6 +106,7 @@ void validate_bootdevices(const char *devices, Error
> **errp);
> void add_boot_device_lchs(DeviceState *dev, const char *suffix,
> uint32_t lcyls, uint32_t lheads, uint32_t lsecs);
> void del_boot_device_lchs(DeviceState *dev, const char *suffix);
> +char *get_boot_devices_lchs_list(size_t *size);
Please add some documentation. At least 'size' must be non-NULL.
Ideally you should add doc for the other functions added in 3/8
"bootdevice: Add interface to gather LCHS" too.
John, what do you think about extracting the *boot_device* functions out
of "sysemu.h"?
Thanks,
Phil.
>
> /* handler to set the boot_device order for a specific type of MachineClass
> */
> typedef void QEMUBootSetHandler(void *opaque, const char *boot_order,
>
