[ipxe-devel] some DOS related questions.

Shao Miller Shao.Miller at yrdsb.edu.on.ca
Mon Aug 1 19:43:41 UTC 2011

On 7/31/2011 14:07, Bernd Blaauw wrote:
> Dear iPXE developers,
> I've noticed the SANBOOT example for booting FreeDOS 1.0 on your 
> project's website (mailing list archives). The default ipxe.iso worked 
> fine for this, provided I used two commands:
> * dhcp
> * sanboot --drive 0x81 http://boot.ipxe.org/freedos/fdfullcd.iso
> if I omit the 0x81 part I'm out of luck because neither harddisk nor 
> ISO are found then (mapping to 0x80 isn't that great apparently).

It's not really common, in my experience, for anything but hard disk 
drives to have BIOS number 0x80.  Personally, I'd be inclined to use 
0xA0 of 0xE0 for an .ISO, as these are common BIOS drive numbers for 
optical disc drives.

> If I add it, the ELTORITO.SYS  ISO9960 driver seems to be able to 
> succesfully 'mount' the ISO.

Excellent. :)

> I've got some questions and suggestions though:
> 1) Where can I find documentation about which NICs are supported? Maybe
> GPXE project lists them, your website at least doesn't seem to do so. 
> I guess each and every one of them is included in the default compiled 
> testing IPXE.ISO file, together with some kind of PCI detection.

I'm actually not sure where there might be a list of supported NICs.  
Sorry. :(  Yes the IDs are all in the binary.

> 2) How do I keep the connection to the internet open and which packet 
> driver can I use? Is it still NIC-dependant or is there a driver that 
> attaches to iPXE? I'm not aware of an UNDIPKT.COM or anything

This is tricky.  If iPXE is providing a SAN connection, that means that 
iPXE is using the network.  If you are running DOS and then hoping to 
have other networking from DOS, you're going to have two programs 
competing for control over the network; not likely to work!  Otherwise, 
you could boot DOS as a MEMDISK (as you mention below) and then use a 
DOS UNDI driver for networking, since iPXE can provide UNDI.

> 3) Is the Flashrom project suitable for your NIC flashing? 
> http://www.flashrom.org for more info.

Probably, but I could be mistaken.

> 4) Is there some option to load this SANBOOT'd ISO into RAM?
> basically Syslinux's memdisk I guess, but then as:
> [ memsanbt http://server.domain.extension/path/filename.iso ]
> From FreeDOS itself this would be easy enough, just wondering if it's 
> possible to do so in advance from iPXE itself. Or I could just use the 
> double ISO trick (Isolinux shell/menu wrapped around inner ISO which 
> can be booted using memdisk)

It's either a SAN-boot or it's not. :)  MEMDISK is a "Linux x86"-format 
"kernel" and the "initrd" is the memory-mapped disk/disc.  So:

   kernel http://server.domain.extension/path/memdisk
   initrd http://server.domain.extension/path/filename.iso

should do the trick.

> I've got a FreeDOS 1.1 test release available at [ 
> http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.1-test3/fd11tst3.iso 
> ] (16MB). No sources atm though, but neither does your ISO :)
> Linking to that FDOS 1.1 ISO through SANBOOT directive is no use, as 
> the HTTP part redirects to [ftp://ftp.ibliblio.org/] (something that 
> modern browsers and WGET/CURL might pick up, but other stuff like 
> HTGET nor your SANBOOT directive seem to be able to.).

Yes but the HTTP SAN expects HTTP as the underlying protocol, most 
likely...  Not FTP.  An FTP SAN protocol would be something new. :)

- Shao Miller

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