[SeaBIOS] First access to the block drive

[Daniel Castro]

On Mon, Mar 5, 2012 at 4:18 AM, Kevin O'Connor <kevin at koconnor.net> wrote:
> On Thu, Mar 01, 2012 at 05:39:25PM +0900, Daniel Castro wrote:
>> Hello all,
>>
>> The xen pv drivers are almost done.
>>
>> When I start the booting process from hda seabios tries to read lba at
>> 0 (sector 0) buffer (buf_fl) to 7c00 count 0 operation 0 (read)
>> command 1 (unlisted)
>> I do not understand count 0 and command 1.
>> Should it be count 1, for the first sector on the drive and a command
>> such as listed in drive.h?
>>
>> Is this normal? Am I missing something?
Thanks for the response Kevin, I am debugging the operation on a xen drive.
Right now the drive fron end is initialized correctly and connects to
the back end, then boot proceeds. But on the first operation is am
getting an command=1 and count=0.

And that seems awkward.

I will take a look at boot_disk() to trace the call.

>
> I don't understand what you are reporting/asking.
>
> The code at boot.c:boot_disk() issues a legacy bios read (int 13 ah=2)
> of the first sector (count=1).
>
> -Kevin

Thanks,

Daniel



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