R: Re: R: Re: R: Re: CAN BIOS/UEFI DO WRITING OPERATIONS ON ATTACHED DRIVES BY MEANS OF INT 13 H INTERRUPT ?

[address@hidden]

Dear Colin,

You has been very clear about the GRUB design.

Please, let me pose another question, because i see you have a solid experience and you are precise.

Do you know if the Ubuntu kernel uses BIOS services, in particular the INT 13H interrupt, or if it is BIOS indipendent ? In this last case in which a way Ubuntu treats the low-level disk services ?

If I well understood Ubuntu should intercept the call and passes it to the operating system's native disk I/O mechanism, bypassing BIOS routines for the low-level disk reading/writing access.

Thanks in advance.

Your tips are welcome.

Best Regards.

Vincenzo.


Forensic Consultant
Tribunale di Lecce

Studio: Strada di Garibaldi - Contrada Paradisi
73010 Lequile (LE)

cell: 339.7968555
skype: vincenzo.di_salvo


> ----Messaggio originale----
> Da: address@hidden
> Data: 18-lug-2017 13.28
> A: "address@hidden"<address@hidden>
> Cc: <address@hidden>
> Ogg: Re: R: Re: R: Re: CAN GRUB DO WRITING OPERATIONS ON ATTACHED DRIVES ?
>
> On Tue, Jul 18, 2017 at 12:38:33PM +0200, address@hidden wrote:
> > I've read with interest your reply and i gave a look at the grub code.
> > 
> > You wrote an important assertion: "GRUB intentionally has no filesystem writing support".
> > 
> > So, the writing operations that grub can do, only be sent to a pre-allocated memory regions of the disk different in any case from that allocated by the OS for the filesystem, where the user data are stored.
> > 
> > This means that grub never can corrupt the user data.
> > 
> > Please, can you confirm if this my conclusion is right ?   Because is this the crucial question i need to solve.
>
> I would never want to rule out the possibility of strange bugs, but that
> is certainly the design.
>
> -- 
> Colin Watson                                       address@hidden