Re: kern/54560: PXE netboot regression

[Andreas Gustafsson <gson%gson.org@localhost>]

The following reply was made to PR kern/54560; it has been noted by GNATS.

From: Andreas Gustafsson <gson%gson.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/54560: PXE netboot regression
Date: Fri, 27 Sep 2019 11:41:09 +0300

 As discussed on tech-kern under the subject "x86 bootstrap features",
 it may be possible to increase the 64k size limit.  With the following
 patch, the boot succeeds for me:
 
 Index: Makefile
 ===================================================================
 RCS file: /cvsroot/src/sys/arch/i386/stand/pxeboot/Makefile,v
 retrieving revision 1.27
 diff -u -r1.27 Makefile
 --- Makefile	23 Sep 2019 13:42:37 -0000	1.27
 +++ Makefile	27 Sep 2019 05:27:41 -0000
 @@ -66,7 +66,7 @@
  #CFLAGS= -O2 -fomit-frame-pointer -fno-defer-pop
  CFLAGS+= -Wall -Wmissing-prototypes -Wstrict-prototypes -Wno-main
  
 -SAMISCCPPFLAGS+= -DHEAP_START=0x10000 -DHEAP_LIMIT=0x30000
 +SAMISCCPPFLAGS+= -DHEAP_START=0x20000 -DHEAP_LIMIT=0x40000
  SAMISCMAKEFLAGS+= SA_USE_CREAD=yes	# Read compressed kernels
  
  CPPFLAGS+= -DPASS_BIOSGEOM
 Index: start_pxe.S
 ===================================================================
 RCS file: /cvsroot/src/sys/arch/i386/stand/pxeboot/start_pxe.S,v
 retrieving revision 1.6
 diff -u -r1.6 start_pxe.S
 --- start_pxe.S	18 Mar 2011 17:46:26 -0000	1.6
 +++ start_pxe.S	27 Sep 2019 05:27:41 -0000
 @@ -69,7 +69,7 @@
  	# set up %ss and %sp
  	movl	$_end, %eax		/* top of bss */
  	shrl	$4, %eax		/* as a segment */
 -	addw	$0x1001, %ax		/* and + 64k */
 +	addw	$0x2001, %ax		/* and + 128k */
  	movw	%ax, %ss		/* for stack */
  	movw	$0xfffc, %sp		/* %sp at top of it */
  
 -- 
 Andreas Gustafsson, gson%gson.org@localhost