Re: NetBSD/zaurus 8.1 problems and possible fixes

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

I wrote:

> (1) Incorrect entry point in kernel LINKFLAGS
 :
> Index: conf/Makefile.zaurus.inc
> ===================================================================
> RCS file: /cvsroot/src/sys/arch/zaurus/conf/Makefile.zaurus.inc,v
> retrieving revision 1.9
> diff -u -p -d -r1.9 Makefile.zaurus.inc
> --- conf/Makefile.zaurus.inc	25 Aug 2015 02:38:15 -0000	1.9
> +++ conf/Makefile.zaurus.inc	22 Oct 2019 04:49:32 -0000
> @@ -20,6 +20,8 @@ SYSTEM_LD_TAIL_EXTRA+=; \
>  KERNEL_BASE_VIRT=	$(LOADADDRESS)
>  
>  KERNLDSCRIPT=		ldscript
> +TEXTADDR=		# defined in ldscript
> +LINKENTRY=		# defined in ldscript
>  
>  EXTRA_CLEAN+=		netbsd.map assym.d ldscript tmp
>  
> ---

> (2) Unexpected zbsdmod.o (Linux kmod) behavior
 :
> Index: stand/zbsdmod/zbsdmod.c
> ===================================================================
> RCS file: /cvsroot/src/sys/arch/zaurus/stand/zbsdmod/zbsdmod.c,v
> retrieving revision 1.9
> diff -u -p -d -r1.9 zbsdmod.c
> --- stand/zbsdmod/zbsdmod.c	2 Dec 2013 18:36:11 -0000	1.9
> +++ stand/zbsdmod/zbsdmod.c	22 Oct 2019 04:49:32 -0000
> @@ -284,6 +284,13 @@ elf32bsdboot(void)
>  		"mov	r1, r1;"
>  		"sub	pc, pc, #4;"
>  		"mov	r1, #(0x00000010 | 0x00000020);"
> +		/*
> +		 * Put the rest of instructions into the same cacheline
> +		 * to make sure no I$ refill after invalidation.
> +		 */
> +		"b	2f;"
> +		".align 5;"
> +		"2:"
>  		"mcr	p15, 0, r1, c1, c0, 0;" /* Write new control register */
>  		"mcr	p15, 0, r1, c8, c7, 0;" /* invalidate I+D TLB */
>  		"mcr	p15, 0, r1, c7, c5, 0;" /* invalidate I$ and BTB */
> 

I've committed these two fixes. (pending-pullups)

> 2. Unaddressed (but workarounded) issue
> 
> (1) Kernel fault 'Alignment Fault 3'

This is not addressed. However it looks options DIAGNOSTIC
can avoid this fault, and commenting out COPY_SYMTAB
is also required in that case to shrink kernel size.
(COPY_SYMTAB consumes ~500KB, but I wonder if zbsdmod.o
 loads symbol table)

> (2) yet another kernel load failure
> 
> The modified above GENERIC kernel works, but when I removed
> the "COPTS" line, "options DIAGNOSTIC", or "COPY_SYMTAB" line,
> the each modified kernel is not loaded (or executed) properly.
> 
> The behavior is similar to the following movie reported
> by Sevan Janiyan on this list back in 2017:
>  https://mail-index.netbsd.org/port-zaurus/2017/04/01/msg000065.html
>  >> https://www.geeklan.co.uk/files/tmp/zaurus3.mov
> 
> I have no idea what happens in this case.

This seems caused by uninitialized kernel BSS on loading kernel
by zbsdmod.o.

With the following change, some kernels (that caused white-out screen
like the above when loaded by the previous zbsdmod.o) are loaded
properly.

Index: compat_linux.h
===================================================================
RCS file: /cvsroot/src/sys/arch/zaurus/stand/zbsdmod/compat_linux.h,v
retrieving revision 1.6
diff -u -p -d -r1.6 compat_linux.h
--- compat_linux.h	11 Dec 2011 14:05:39 -0000	1.6
+++ compat_linux.h	26 Oct 2019 14:26:05 -0000
@@ -64,6 +64,7 @@ extern	int register_chrdev(unsigned int,
 extern	int unregister_chrdev(unsigned int, const char *);
 extern	void printk(const char *, ...) __printflike(1, 2);
 extern	void *memcpy(void *, const void *, size_t);
+extern	void *memset(void *, int, size_t);
 
 /* procfs support */
 struct proc_dir_entry {
Index: zbsdmod.c
===================================================================
RCS file: /cvsroot/src/sys/arch/zaurus/stand/zbsdmod/zbsdmod.c,v
retrieving revision 1.10
diff -u -p -d -r1.10 zbsdmod.c
--- zbsdmod.c	26 Oct 2019 09:58:40 -0000	1.10
+++ zbsdmod.c	26 Oct 2019 14:26:05 -0000
@@ -262,6 +262,10 @@ elf32bsdboot(void)
 				    (((char *)elf) + phdr[i].p_offset)[sz];
 			}
 		}
+		if (IS_BSS(phdr[i])) {
+			memset((void *)(phdr[i].p_vaddr + phdr[i].p_filesz), 0,
+			    phdr[i].p_memsz - phdr[i].p_filesz);
+		}
 	}
 
 	addr = (int *)(elf->e_entry);


---
Izumi Tsutsui