[syslinux] Status of support for secotr sizes >512b

[Ady]

> Hello,
> 
> can someone give me a short summary on the status of support for sector
> sizes >512bytes in SYSLINUX?
> 
> The installer obviously still doesn't support it, at least it complains
> about "unsupported sector size" when used on a 4k-sector disk. I read
> somewhere that this is only a problem of the installer, and that
> SYSLINUX itself would work if it got installed "by other tools".
> Unfortunately, I found no hint as to what other tools could be used for
> this.
> 
> Thanks,
> Andreas
 
Yes, that's the current status.

_ Many (partition editor, filesystem formatting and other) tools do not 
correctly support bytes_per_sector values other than 512.

_ Many BIOSes do not correctly support bytes_per_sector values other 
than 512.

_ syslinux.efi should have no problem with 4096 bytes per sector.

_ chain.c32 should have no problem with 4096 bytes per sector.

_ Some multiple-connectors devices (e.g. with both, USB and SATA or 
eSATA connectors or external drive enclosures) might use (or present 
themselves, or show, or report, or force) a different bytes_per_sector 
value, depending on which type of connection / controller is used. 
There _might_ be workarounds in some of these cases (e.g. using some 
steps involving "loop" devices, instead of directly referring to the 
original device).

_ Some devices have 4096 bytes per sectors, but are able to use a 512 
bytes per sector "logical" value ("512e").

_ There might be a need to use the "55AA" magic number signature for 
the MBR and for VBRs in *every* "510-511th" byte count (counting from 
zero to 511) of the corresponding sectors; i.e. the "55AA" magic number 
should better be present 8 times in a 4096 bytes_per_sector MBR and/or 
VBRs, once every 512 bytes in the relevant sectors. These magic values 
might need to be introduced / edited manually.

_ Other conditions, not necessarily related to 4096 bytes per sector 
but regarding Syslinux, might be required (e.g as of 6.03, Syslinux 
supports a 4KiB_per_cluster value for NFTS, but bigger values are not 
yet supported).

_ If some auxiliary tool manages to install SYSLINUX/EXTLINUX on a "4k" 
device, then Syslinux should have no problem with 4096 bytes per 
sector.


I don't know how much stable / usable / predictable the behavior of 
other bootloaders is on this type of devices.

So, it is not just a matter of Syslinux supporting these devices; there 
are other factors in play.

Regards,
Ady.
 
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