[gPXE] Only register bios drive without booting

[Andrey Kuzmin]

> In regards to your request to use gPXE to register a drive but not boot
> from it, the "Install direct to SAN" link from the "HowTo Guides" lands
> you here[1].  That might help for understanding the "keep-san" setting
> and how it can be used to maintain the iSCSI connection after control
> returns back to gPXE from an unbootable MBR.

I've read this so many times so could retell what is written here from
head :))

> If you have a valid MBR on the SAN and no active partitions, return
> should control back to gPXE.

That could be mine problem. Partion is active now, may be that's why I
could not return to gPXE.

OK. Let me describe what I'm trying to do with Windows 7 installation.

Straightforward  installation  do  not  work due to "Windows cannot be
installed  to  this  disk.  This  computer's  hardware may not support
booting  to this disk. Ensure that the disk's controller is enabled in
the computer's BIOS menu" warning.

So  I've  attached  HDD and then Win7 installed to iSCSI, but it seems
that  wrote  boot  files  to  HDD  instead  of iSCSI, so after install
sanboot   writes   something  like  "cannot boot from this drive", but
booting  from  HDD  starts  and  fails  telling that there are no some
windows files (those are on iSCSI).

Then I've  tried  to  make partion on iSCSI as active and got what was sent
on the first email.

Might be I'm just doing something wrong...