[syslinux] [RFC] COMBOOT: readdir: st_mode or d_type

Gene Cumm gene.cumm at gmail.com
Wed Mar 4 05:07:15 PST 2009


On Wed, Mar 4, 2009 at 2:12 AM, Thomas Schmitt <scdbackup at gmx.net> wrote:
> Hi,
>
> Gene Cumm wrote:
>>  my goal would be to duplicate the
>> functionality that searchdir provides in readdir as far as the name
>> and such.
>
> A file in an ISO 9660 filesystem can have up
> to 4 different names:
> - dull ISO name: much like in FAT
> - Rock Ridge name: much like in ext2
>  compliant to X/Open System Interface.
> - Joliet name: like NTFS ?
> - ISO-9660:1999 name: a second dull ISO name ?
>  (This seems to be rarely produced.)
>
> Which one to pick ?
> It seems to me that it is about the users'
> expectation. This expectation is probably
> formed by the daily experience on operating
> systems.
> That would be:
> - dull ISO for DOS
> - Joliet for Windows
> - Rock Ridge for X/Open systems

Need to check what ISOLINUX searchdir does.  I'm contemplating between
ISOLINUX and EXTLINUX for my next endeavor.  EXTLINUX would probably
be more complex to code/debug and less often used but rebuilding a
filesystem is quick and easy for upgrading EXTLINUX (no remaster of
ISO).

>
>> > Expect at least two groups of read positions which
>> > are used frequently and are several hundred KB apart.
>>
>> Ouch.  That'll do a nice job on performance
>
> Especially since optical media are really poor
> with random access reading. If the directory tree

Especially the slim drives found in laptops and the slimline desktops.

I think Syslinux can only buffer about 64k (1 segment) if I'm reading
core/cache.inc correctly.  The next question is how much data would a
user need cached if they were performing ls repeatedly on a normal
size boot system.  I'd expect that it should be under half that but
I'm uncertain.

If more cache is needed, one idea is to attempt a redesign where in CS
there will exist a dword variable holding the value of the segment of
the master table of cache sectors.  From there, there could be
segment:offset values from which the cache can be obtained.

-- 
-Gene

"No one ever says, 'I can't read that ASCII E-mail you sent me.'"




More information about the Syslinux mailing list