On 9/26/19 8:26 PM, John Snow wrote:
> On 9/26/19 5:57 AM, Philippe Mathieu-Daudé wrote:
>> 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.
>>
>
> I think it's okay to do it at the bottom of the loop. No real benefit to
> being that eager to free resources in my mind. I expect setup at the top
> of a block and teardown at the bottom of a block.
>
> Trying to do too much in the middle gets messy in my opinion, not that
> it seems to matter here.
No problem.
>>> +
>>> + 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?
>>
>
> :D
>
>>> + 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.
>>
>
> Sure; but I wasn't going to gate on it because this series went unloved
> for so long. At this point, a follow-up patch is fine.
OK
>
>> Ideally you should add doc for the other functions added in 3/8
>> "bootdevice: Add interface to gather LCHS" too.
>>
>
> Same thing here.
>
>> John, what do you think about extracting the *boot_device* functions out
>> of "sysemu.h"?
>>
>
> Potentially worthwhile; but not critical at the moment. The source tree
> is not the best-organized thing as-is and I don't think it's fair to
> hold this series up for much longer for nice-to-haves, ultimately.
>
> More targeted improvements might avoid the "whose responsibility is it
> to stage this?" hot potato we played with this one; so I'd rather have
> smaller follow-up patches handled by the respective maintainers.
Sure, fair enough.
>
>> Thanks,
>>
>> Phil.
>>
> Thanks for the reviews :)
:)
