Legacy Firmware/INT 13H supporting >512 byte sectors?

Legacy Firmware/INT 13H supporting >512 byte sectors?

[Mihai Moldovan]

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Hi


Just a quick question: did anyone ever come up a BIOS firmware that supports
sector sizes higher than 512 bytes (say 4096 bytes)?



Mihai


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Re: Legacy Firmware/INT 13H supporting >512 byte sectors?

[Vladimir 'phcoder' Serbinenko]

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пт, 17 авг. 2018 г., 17:14 Mihai Moldovan <ionic@ionic.de>:

> Hi
>
>
> Just a quick question: did anyone ever come up a BIOS firmware that
> supports
> sector sizes higher than 512 bytes (say 4096 bytes)?
>
Sure. Any BIOS able to read CD supports 2K sectors.
If you mean HDD then I have never seen one. I wrote support for non-512B
sectors in GRUB but so far it's untested as I couldn't find such a BIOS

>
>
>
> Mihai
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>

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Re: Legacy Firmware/INT 13H supporting >512 byte sectors?

[Mihai Moldovan]

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[resent to list, since I forgot to add a CC header]

* On 08/17/2018 06:11 PM, Vladimir 'phcoder' Serbinenko wrote:
> Sure. Any BIOS able to read CD supports 2K sectors.
> If you mean HDD then I have never seen one. I wrote support for non-512B sectors
> in GRUB but so far it's untested as I couldn't find such a BIOS

Ah, of course. CD sectors are 2K big. Yeah, that makes sense.

I meant HDD sectors, yes.


My firmware is doing weird things: it always reports a sector size of 512 bytes,
reads and outputs data in 512 byte chunks, but sector addressing is actually
HDD-dependent (i.e., for 4Kn drives 4K-based).

I'll work around that using some heuristic, but that's only part of the problem.


The bigger issue will probably be the boot image, which likely is too small to
incorporate sophisticated code. I guess I could trick THAT into behaving
correctly by spreading the core image file out over several sectors and only
using the first 512 bytes of each sector.



Mihai




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Re: Legacy Firmware/INT 13H supporting >512 byte sectors?

[Toomas Soome]

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> On 17 Aug 2018, at 21:01, Mihai Moldovan <ionic@ionic.de> wrote:
> 
> [resent to list, since I forgot to add a CC header]
> 
> * On 08/17/2018 06:11 PM, Vladimir 'phcoder' Serbinenko wrote:
>> Sure. Any BIOS able to read CD supports 2K sectors.
>> If you mean HDD then I have never seen one. I wrote support for non-512B sectors
>> in GRUB but so far it's untested as I couldn't find such a BIOS
> 
> Ah, of course. CD sectors are 2K big. Yeah, that makes sense.
> 
> I meant HDD sectors, yes.
> 
> 
> My firmware is doing weird things: it always reports a sector size of 512 bytes,
> reads and outputs data in 512 byte chunks, but sector addressing is actually
> HDD-dependent (i.e., for 4Kn drives 4K-based).
> 
> I'll work around that using some heuristic, but that's only part of the problem.
> 
> 
> The bigger issue will probably be the boot image, which likely is too small to
> incorporate sophisticated code. I guess I could trick THAT into behaving
> correctly by spreading the core image file out over several sectors and only
> using the first 512 bytes of each sector.
> 


Yes there are systems supporting  BIOS INT13, see https://www.illumos.org/issues/8303 <https://www.illumos.org/issues/8303> for reference.

rgds,
toomas

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