[syslinux] wiki account request

[Gene Cumm]

On Wed, Jan 22, 2014 at 3:20 AM, Thomas Schmitt <scdbackup at gmx.net> wrote:
>
> Now in a new thread with updated subject.
>
> ----- Forwarded message from Thomas Schmitt -----
>
> Date: Wed, 22 Jan 2014 08:45:51 +0100
>>From: Thomas Schmitt
> To: syslinux at zytor.com
> Subject: Re: [syslinux] Advice/directions to users of Syslinux
> Message-Id: <29490645553171871372 at scdbackup.webframe.org>
> Reply-To: For discussion of Syslinux and tftp-hpa <syslinux at zytor.com>
>
> Hi,
>
> i now realized that
>   http://www.syslinux.org/wiki/index.php/Hardware_Compatibility#USB-Geometry
>   http://www.syslinux.org/wiki/index.php/Hardware_Compatibility#USB-Miscellaneous
> are the new wiki sections by Gene Cumm. (Sorry for not reading
> them when they were announced.)
>
> So i ask especially him whether the statement
>
>  "An examle is a drive of 128,64,32 with a partition ending at
>   127,63,32 (the last sector of the last whole cylinder)."
>
> should be changed and expanded to
>
>  "An example is a drive of size of 128 MB (or slightly larger)
>   assumed with 64 heads per cylinder and 32 sectors per head,
>   where the partition should end at 127,63,32.
>   Drives larger than 1 GB should be regarded as having 255 heads
>   per cylinder and 63 sectors per head. E.g. an drive of
>   15794176 blocks (7.5 GB) should have its partition end
>   at 982,254,63.
>   Drives larger than 16434495 blocks should bear as partition
>   end 1023,254,63. Setting the partition end LBA to the full drive
>   size may or may not hamper its bootability."
>
> Reasoning:
>
> I state "assumed with 64 heads per cylinder and 32 sectors per head"
> because the values of H/C and S/H are more or less a deliberate
> decision at partitioning time.
>
> I refrain from giving the drive size in CHS, because this is ambigous
> until the user has chosen H/C and S/H.
>
> I do not use digit separators with decimal naumers (15,794,176
> versus 15794176) because this could get confused with the CHS
> commas.
>
> I mention the opportunity to set the end LBA higher than the end CHS
> because else half of a 16 GB drive would be wasted.
> But maybe one should rather state that if a BIOS is too dumb for
> uneven partiton endings, then it is probably too dumb for large
> partitions, too.
> Any experience around ? Any opinions ?
>
> The advise to set large drive ends to 1023,254,63 is taken from
>   http://en.wikipedia.org/wiki/Master_boot_record#Partition_table_entries

Excellent point.  Thank you.  I was merely thinking of a relatively
easy scenario that could confuse BIOSs/firmwares and cause them to
ignore the drive.

> ---------------------------------------------------------
> To the wiki admins:
>
> I acquired a SYSLINUX wiki account: "scdbackup"
> Please enable editing.

Done.

> Have a nice day :)
>
> Thomas

Thanks.  Enjoy.

-- 
-Gene