Syslinux - Apr 2003 - COM32 Question

Does the COMBOOT stuff with 2.04 work correctly with function calls?
or does one need to write it as one huge function?

If memory serves me correctly, there was some problem if hello.c
was modified to include additional functions, in an earlier
version.

- Murali

ganapathy murali krishnan wrote:
> Does the COMBOOT stuff with 2.04 work correctly with function calls?
> or does one need to write it as one huge function?
> 
> If memory serves me correctly, there was some problem if hello.c
> was modified to include additional functions, in an earlier
> version.
> 
Mostly a red herring.  As long as you include c32entry.o (from
sample/c32entry.S) first on the link line you should be just fine.

	-hpa

Thanks for the reply. I just assumed that since BIOS numbers heads and 
cylinders from 0, that sectors are also numbered from zero.

I expect to finish writing my COM32 code in a couple of days. Basically, 
it consists of two utilities. One (runs in Linux) reads a list of images
to execute from a file and writes it to sector 6-9 of the hard disk.
The other (COM32 code), reads this information and boots into the 
appropriate kernel and removes the first entry, so that the next time
it boots into the second kernel....

If you think it will be useful, I can send the code and you can include 
it as a sample code in SYSLINUX. Since I did not write this code with 
effeciency in mind, the .c32 file is large (5K).

Question: Can similar code be written to handle SCSI hard disks as well? 
Meaning, is it just as easy. If so, could you point me and the right 
BIOS interrupt to use. My initial searches all talked about SCSI drivers 
which is not a possibility for a COM32 code.

- Murali

H. Peter Anvin wrote:
> ganapathy murali krishnan wrote:
> 
>>The checkstatus function says there was no problem executing the system
>>call. Is there is any nice way to debug COM32 code?
>>
> 
> 
> What I usually do is use a simulator, like Bochs.
> 
> 
>>NUM_SECT=4, SECT_START=6 and BUFSIZE=512*NUM_SECT.
>>
> 
> 
> Sector numbering starts at 1, not 0.  Therefore this is the equivalent
> of "skip=5", not "skip=6".
> 
> 	-hpa
> 
>

Murali Krishnan Ganapathy wrote:
> 
> Question: Can similar code be written to handle SCSI hard disks as well? 
> Meaning, is it just as easy. If so, could you point me and the right 
> BIOS interrupt to use. My initial searches all talked about SCSI drivers 
> which is not a possibility for a COM32 code.
> 
SCSI disks use the same interrupt as all other hard disks.  So, in other 
words, it already does support SCSI.

	-hpa