[syslinux] [PATCH 1/5] fat: fix minfatsize for large FAT32

Gene Cumm gene.cumm at gmail.com
Fri Feb 26 09:54:03 PST 2016

On Fri, Feb 26, 2016 at 8:10 AM, Pete Batard via Syslinux
<syslinux at zytor.com> wrote:
> Hi Gene,
> On 2016.02.26 11:49, Gene Cumm wrote:
>> I think there may be another answer to this:
>> 1) a tool to fix the broken FSs by "wasting" the high clusters of the
>> file system, a non-destructive correction.  As it stands they're
>> effectively wasted already and might risk a user thinking the file
>> system isn't full when in fact the FAT itself is.
> I'm not exactly sure how that would work (how would you mark those clusters
> as wasted when my understanding is that the FAT's can't provide any
> knowledge about them in the first place?) and unless it is automatically
> integrated and ran during the Syslinux installation, it sounds quite
> inconvenient for users.

Total size and last-known free space should be adjusted accordingly.
I don't think there's anything more but a fsck/chkdsk or similar tool
should also be able to fix this error.  Ending the file system before
the end of the partition may seem unusual but helps in this instance.

>> 2) The recommendation to use the Syslinux installer's "-f" flag until
>> the individual file system is corrected with the above tool, assuming
>> "-f" circumvents this check.  I've been tossing the idea around that a
>> single "-f" might not be the best answer and a longer option
>> specifying a list of checks to skip might be more balanced, ie "-F
>> minfatsize,othercheck".
>> 3) Ensure that the Syslinux installers state which check failed to
>> assist users in correcting their file system, regardless of if "-f" is
>> specified.  If "-f" is not specified, installation should fail
>> completely (hopefully with 0 alterations).  If "-f" is specified but
>> not necessary (indicating a user/tool that isn't being cautious),
>> consider throwing a warning while still allowing the install and
>> returning a success to the caller of the installer.
> Joining on what you advocate above, I think I'd indeed prefer an installer
> that fails when -f isn't used, with an explicit message stating why (maybe
> with a computation of the number of sectors that cannot be addressed, so
> that users have a good idea of the wastage) along with an indication that
> they can use '-f' use to bypass that check, should they want to.
> Since I brought this whole thing up, and provided this is the course of
> action everybody agrees on, I *may* try to work on a patch that does this...
> bearing in mind that, as you know, the last time I said I'd work out some
> patches for Syslinux (this series), it took about 3 months before I posted
> anything. ;)

Thinking now. perhaps automating a check and/or fix into a tool
running a Syslinux installer might be a good idea.


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