[Qemu-devel] Re: [PATCH 0/3 v2] allow online resizing of block devices

[Juan Quintela <quintela@redhat.com>]

Christoph Hellwig <hch@lst.de> wrote:
> This patchset adds support for online resizing of block devices.
>
> The first patch adds a new resize monitor command which call into
> the existing image resize code.  This is the meat of the series
> and probably needs quite a bit of review and help as I'm not sure
> about how to implement the error handling for monitor commands
> correctly.  Am I really supposed to add a new QERR_ definition
> for each possible error?  And if yes how am I supposed to define
> them?  The macros for them aren't exactly self-explaining.
>
> The second patch adds a way to tell drivers about a resize, and the
> third one adds a guest notification for config changes to virtio-blk
> which allows the guest to pick it up without a rescan.  I've just sent
> the corresponding Linux guest driver patch to Rusty.
>
> Changes from version 1 to version 2:
>  - also add a QMP command (block_resize)
>  - use the o format for the size in the monitor command
>  - fix typos
>  - use QERR_UNDEFINED_ERROR for errors instead of unstructured strings
>  - remove the CDROM hint check
>  - add a reason argument to the change callback

Does this handle the change of the rtc data?  I can't see how/where.
(Not that I know if it is important at all until reboot).

cmos_init_hb() uses the size to guess the right geometry of the drives,
if we change the size of the drive, should we change that one?



Later, Juan.

hw/pc.c
static void pc_cmos_init_late(void *opaque)
{
    pc_cmos_init_late_arg *arg = opaque;
    ISADevice *s = arg->rtc_state;
    pint val;
    BlockDriverState *hd_table[4];
    int i;

    ide_get_bs(hd_table, arg->idebus0);
    ide_get_bs(hd_table + 2, arg->idebus1);

    rtc_set_memory(s, 0x12, (hd_table[0] ? 0xf0 : 0) | (hd_table[1] ? 0x0f : 0));
    if (hd_table[0])
        cmos_init_hd(0x19, 0x1b, hd_table[0], s);
    if (hd_table[1])
        cmos_init_hd(0x1a, 0x24, hd_table[1], s);

.....
}

static void cmos_init_hd(int type_ofs, int info_ofs, BlockDriverState *hd,
                         ISADevice *s)
{
    int cylinders, heads, sectors;
    bdrv_get_geometry_hint(hd, &cylinders, &heads, &sectors);
    rtc_set_memory(s, type_ofs, 47);
    rtc_set_memory(s, info_ofs, cylinders);
    rtc_set_memory(s, info_ofs + 1, cylinders >> 8);
    rtc_set_memory(s, info_ofs + 2, heads);
....