[syslinux] memdisk, free memory
H. Peter Anvin
hpa at zytor.com
Thu Jan 18 11:11:59 PST 2007
Michael Redinger wrote:
> Hm, not sure if this output is needed:
> First, I boot from a floppy disk. mem /c says (at the end) that there
> are 638 K total conventional memory ( 188K used, 380K free).
> Then I take that floppy and write a floppy image (using dd) and boot
> that floppy via PXE (kernel memdisk; append initrd=my.img keeppxe).
> Now mem /c says that there is only 568K total memory (188K used, 380K
> free) (the actual amount of total conventional memory found depends on
> the network card).
>> That way you can see if it's a PXE issue or not. When using MEMDISK on
>> top of Isolinux, only 2KB of conventional RAM is eaten away.
> See above - it is much more with pxelinux. 2KB (that's what the memdisk
> webpage says, too) would be perfect! :-)
And it would, if you didn't have "keeppxe" -- that'll sometimes eat up
several hundred kilobytes.
> Btw., I just tried a Siemens laptop with a Realtek network card (just to
> add one more to the list that does not work).
>> The rest is eaten away by plain old DOS programs (kernel, shell,
>> drivers) which can be optimised using old DOS tricks.
>> How much memory do you need in DOS, and does that include network access
>> as well through MC Client?
>> Or are you just booting from network, then doing something on local
>> machine instead? (get rid of the KEEPPXE statement then in pxelinux's
>> config file).
> Well, I need keeppxe because I want to load the Microsoft IP stack.
> This used to work, but to access certain fileservers, I have to replace
> net start workstation
> net start full
> because I need full redirector support. With the floppy, there is enough
> free memory available, but after PXE boot it is simply not enough.
> I tried optimizing the DOS part, but I don't manage to get enough free
> memory - the network part and the missing memory together are simply too
> much ...
> Btw., I am using the "MSNET" version of the nwdsk boot floppy (which is
> based on the bart bootdisk, IIRC).
You're asking to have it both ways. That PXE stack you're asking to
keep isn't small.
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