On Sun, Nov 14, 2010 at 8:54 PM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> On Sun, Nov 14, 2010 at 08:49:59PM +0000, Blue Swirl wrote:
>> On Sun, Nov 14, 2010 at 3:39 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
>> >
>> > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
>> > ---
>> > Âhw/fw_cfg.c | Â 14 ++++++++++++++
>> > Âhw/fw_cfg.h | Â Â4 +++-
>> > Âsysemu.h  Â|  Â1 +
>> > Âvl.c    Â|  51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> > Â4 files changed, 69 insertions(+), 1 deletions(-)
>> >
>> > diff --git a/hw/fw_cfg.c b/hw/fw_cfg.c
>> > index 7b9434f..f6a67db 100644
>> > --- a/hw/fw_cfg.c
>> > +++ b/hw/fw_cfg.c
>> > @@ -53,6 +53,7 @@ struct FWCfgState {
>> > Â Â FWCfgFiles *files;
>> > Â Â uint16_t cur_entry;
>> > Â Â uint32_t cur_offset;
>> > + Â ÂNotifier machine_ready;
>> > Â};
>> >
>> > Âstatic void fw_cfg_write(FWCfgState *s, uint8_t value)
>> > @@ -315,6 +316,15 @@ int fw_cfg_add_file(FWCfgState *s, Âconst char *filename, uint8_t *data,
>> > Â Â return 1;
>> > Â}
>> >
>> > +static void fw_cfg_machine_ready(struct Notifier* n)
>> > +{
>> > + Â Âuint32_t len;
>> > + Â Âchar *bootindex = get_boot_devices_list(&len);
>> > +
>> > + Â Âfw_cfg_add_bytes(container_of(n, FWCfgState, machine_ready),
>> > + Â Â Â Â Â Â Â Â Â Â FW_CFG_BOOTINDEX, (uint8_t*)bootindex, len);
>>
>> I started to implement this to OpenBIOS but I noticed a small issue.
>> First the first byte must be read to determine length. Then the read
>> routine will be called again to read the correct amount of bytes. This
>> would work, but since there is no shortage of IDs, I'd prefer a system
>> where one ID is used to query the length and another ID is used to
>> read the data, without the length byte. This is similar how command
>> line, initrd etc. are handled.
>>
>> This would have the advantage that since fw_cfg uses little endian
>> format, the length value would easily scale to for example 64 bits to
>> support terabytes of boot device lists. ;-)
>
> Yea. Let's just print # of devices as a property, in ASCII.
> No endian-ness, no nothing.
> Also - can we just NULL-terminate each ID?
No, we should use LE numbers like other IDs. To be more specific, this
is what I meant (instead of FW_CFG_BOOTINDEX):
FW_CFG_BOOTINDEX_LEN: get LE integer length of the boot device data.
FW_CFG_BOOTINDEX_DATA: get the boot device data as NUL terminated C
strings, all strings back-to-back. The reader can determine number of
strings.
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