Philippe, thanks for the fast review,
John, thanks for picking up this hot potato :-)
Sam
On Thu, Sep 26, 2019 at 10:16 PM Philippe Mathieu-Daudé <phi...@redhat.com>
wrote:
> On 9/26/19 9:09 PM, Philippe Mathieu-Daudé wrote:
> > 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.
>
> I forgot:
> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
>
