PXE boot

[Sinha, Prokash]

On 9/4/14 2:22 PM, "Sinha, Prokash" <psinha at panasas.com> wrote:

>Yeah, something going on that I don't understand. I defined that macro,
>and for quick verify -
>make -v 
>Warning: Object directory not changed from original
>/.automount/nfs.paneast.panasas.com/root/home/psinha/psinha-bug-pa/src/fre
>e
>bsd-c/sys/boot/i386/pxeldr
>cc -O2 -fno-strict-aliasing -pipe  -ffreestanding
>-mpreferred-stack-boundary=2  -mno-mmx -mno-3dnow -mno-sse -mno-sse2
>-mno-sse3 -m32 -march=i386 -DALWAYS_SERIAL  -c pxeldr.S
>cc -O2 -fno-strict-aliasing -pipe  -ffreestanding
>-mpreferred-stack-boundary=2  -mno-mmx -mno-3dnow -mno-sse -mno-sse2
>-mno-sse3 -m32 -march=i386 -DALWAYS_SERIAL   -nostdlib -m elf_i386_fbsd -N
>-e start -Ttext 0x7c00 -Wl,-S,--oformat,binary -o pxeldr pxeldr.o
>make: don't know how to make pxeboot.8. Stop
>
>==> The variable is defined and the correct flag is included in the cc ...
>
>
>But I still don't get the messages from pxe_enable or pxe_init...
>
>Need to sit back and look further...
>
>John, much appreciated for the help...
>
>If anything else you can think of, please drop couple lines for me to
>investigate...
>-prokash
>
>On 9/4/14 10:53 AM, "John Baldwin" <jhb at freebsd.org> wrote:
>
>>On Thursday, September 04, 2014 04:33:46 PM Sinha, Prokash wrote:
>>> On 9/4/14 9:31 AM, "Sinha, Prokash" <psinha at panasas.com> wrote:
>>> >Thanks once again...
>>> >
>>> >This is the part - that you spelled out is why I had a trace in the
>>> >pxe_enable(...) routine. As well as at pxe_init( ...) routine, just to
>>>be
>>> >sure
>>> >the pxe.c routines are working like ( as you said ) devsw invocation.
>>>But
>>> >did not see the trace messages, could be serial console is not acting
>>>(
>>> >though I doubt it).
>>> >
>>> >Now gave me a base, off of what I could debug ...
>>
>>Hmm, the console should be working (cons_probe() is called before
>>pxe_enable()).  However, if you are using 'console=comconsole' in
>>loader.conf 
>>to set a serial console, you won't see early messages because loader.conf
>>is 
>>processed after main() calls interact() at the bottom of the function.
>>If you 
>>want to see early loader messages on serial, you will need to build
>>pxeboot 
>>with BOOT_PXELDR_ALWAYS_SERIAL defined as a make variable (so on the
>>command 
>>line, or in /etc/make.conf or /etc/src.conf).  That will force a serial
>>console for early loader messages.
>>
>>> >
>>> >-prokash
>>> >
>>> >On 9/4/14 7:57 AM, "John Baldwin" <jhb at freebsd.org> wrote:
>>> >>On Wednesday, September 03, 2014 11:16:05 PM Sinha, Prokash wrote:
>>> >>> Thanks much, John !
>>> >>> 
>>> >>> When it starts executing ? How ?. Who starts executing these. From
>>>the
>>> >>> Makefile it's org is 0x7c00. So I would assume that it would be
>>>loaded
>>> >>>
>>> >>>at
>>> >>>
>>> >>> that absolute real-mode address !. I don't understand this part.
>>>But,
>>> >>>
>>> >>>if I
>>> >>>
>>> >>> put traces, I see pxe_open, and pxe_close are being called, but
>>>after
>>> >>>
>>> >>>all
>>> >>>
>>> >>> these pxe_calls are done, the loader's main is invoked at Rebooting
>>>Š
>>> >>>
>>> >>>time.
>>> >>>
>>> >>> We are using a net boot server, and I see mountd- authenticated Š
>>> >>>
>>> >>>message
>>> >>>
>>> >>> storm on the boot server side.
>>> >>> 
>>> >>> Wondering what could cause such a message storm, while pxe_open()
>>>->
>>> >>>
>>> >>>net
>>> >>>
>>> >>> if_open( ) executes.
>>> >>
>>> >>The PXE BIOS uses TFTP to fetch the pxeboot binary (and it will do
>>>its
>>> >>own
>>> >>DHCP, etc. as part of doing that).  It writes the binary it downloads
>>> >>starting
>>> >>at address 0x7c00.  Once the download is complete, it jumps to 0x7c00
>>> >>similar
>>> >>to how booting from a disk loads the first sector at address 0x7c00
>>>and
>>> >>then
>>> >>jumps to it.
>>> >>
>>> >>The PXE calls in libi386 should not be invoked until the loader
>>>main()
>>> >>routine
>>> >>
>>> >>runs:
>>> >>    /*
>>> >>    
>>> >>     * Special handling for PXE and CD booting.
>>> >>     */
>>> >>    
>>> >>    if (kargs->bootinfo == 0) {
>>> >>	
>>> >>	/*
>>> >>	
>>> >>	 * We only want the PXE disk to try to init itself in the below
>>> >>	 * walk through devsw if we actually booted off of PXE.
>>> >>	 */
>>> >>	
>>> >>	if (kargs->bootflags & KARGS_FLAGS_PXE)
>>> >>	
>>> >>	    pxe_enable(kargs->pxeinfo ? PTOV(kargs->pxeinfo) : NULL);
>>> >>	
>>> >>	else if (kargs->bootflags & KARGS_FLAGS_CD)
>>> >>	
>>> >>	    bc_add(initial_bootdev);
>>> >>    
>>> >>    }
>>> >>
>>> >>That enables the PXE devsw driver so that it will do something later
>>>when
>>> >>
>>> >>main() calls all the devsw init routines:
>>> >>    /*
>>> >>    
>>> >>     * March through the device switch probing for things.
>>> >>     */
>>> >>    
>>> >>    for (i = 0; devsw[i] != NULL; i++)
>>> >>	
>>> >>	if (devsw[i]->dv_init != NULL)
>>> >>	
>>> >>	    (devsw[i]->dv_init)();
>>> >>    
>>> >>    printf("BIOS %dkB/%dkB available memory\n", bios_basemem / 1024,
>>> >>
>>> >>bios_extmem / 1024);
>>
>>-- 
>>John Baldwin
>