On Sat, 19 Nov 2005, Denis Vlasenko wrote:
> On Friday 18 November 2005 16:15, linux-os (Dick Johnson) wrote:
>> On Fri, 18 Nov 2005, Denis Vlasenko wrote:
>>
>>> On Thursday 17 November 2005 20:51, linux-os (Dick Johnson) wrote:
>>>> It appears as though Linux is still restarting as a "warm boot",
>>>> rather than a cold boot (in other words, putting magic in the
>>>> shutdown byte of CMOS) so the hardware doesn't get properly
>>>> initialized. Would somebody please check this out. When changing
>>>> operating systems, you need a cold-boot.
>>>
>>> Can you check which driver does that? The test would be to
>>> boot a special Linux setup which reboots immediately
>>> (say, wuth init=/some/reboot_script.sh boot param).
>>>
>>> Then start removing drivers from kernel until you
>>> can boot Win successfully after Linux reboots.
>>> --
>>> vda
>>
>> I booted into a shell from a floppy disk. There were no drivers
>> installed, not even the IDE driver. I could not reboot windows
>> after linux was up and rebooted. This was Linux-2.6.13.4. Then
>> I tried linux-2.4.26 which corresponds to the version when I
>> first reported this problem. The same thing happens. Therefore,
>> I temporarily modified linux-2.6.13.4 to force a triple-fault
>> and processor reset when doing a reboot. With this temporary
>> modification it is possible to boot windows after Linux was
>> running.
>>
>> This is the reboot patch. It is not a "solution", just something
>> that shows that the current reboot code doesn't force the BIOS
>> to start from scratch, which is essential when changing operating
>> systems.
>>
>>
>> --- linux-2.6.13.4/arch/i386/kernel/reboot.c.orig 2005-11-18 08:29:12.000000000 -0500
>> +++ linux-2.6.13.4/arch/i386/kernel/reboot.c 2005-11-18 08:52:40.000000000 -0500
>> @@ -337,6 +337,11 @@
>>
>> void machine_restart(char * __unused)
>> {
>> + for(;;) {
>> + __asm__ __volatile__("\tmovl %cr0, %eax\n"
>> + "\tandl $~0x80000000, %eax\n"
>> + "\tmovl %eax, %cr0\n");
>> + }
>> machine_shutdown();
>> machine_emergency_restart();
>> }
>
> Does reboot=cb ('cold', 'thru BIOS') work for you?
>
> I read arch/i386/kernel/reboot.c and it looks like reboot=cb
> kernel param will triple fault too:
>
> static int reboot_mode;
> static int reboot_thru_bios;
>
> static int __init reboot_setup(char *str)
> {
> while(1) {
> switch (*str) {
> case 'w': /* "warm" reboot (no memory testing etc) */
> reboot_mode = 0x1234;
> break;
> case 'c': /* "cold" reboot (with memory testing etc) */
> reboot_mode = 0x0;
> break;
> case 'b': /* "bios" reboot by jumping through the BIOS */
> reboot_thru_bios = 1;
> break;
> case 'h': /* "hard" reboot by toggling RESET and/or crashing the CPU */
> reboot_thru_bios = 0;
> break;
> }
> if((str = strchr(str,',')) != NULL)
> str++;
> else
> break;
> }
> return 1;
> }
>
> __setup("reboot=", reboot_setup);
> ...
> void machine_emergency_restart(void)
> {
> if (!reboot_thru_bios) {
> if (efi_enabled) {
> efi.reset_system(EFI_RESET_COLD, EFI_SUCCESS, 0, NULL);
> load_idt(&no_idt);
> __asm__ __volatile__("int3");
> }
> /* rebooting needs to touch the page at absolute addr 0 */
> *((unsigned short *)__va(0x472)) = reboot_mode;
> for (;;) {
> mach_reboot_fixups(); /* for board specific fixups */
> mach_reboot();
> /* That didn't work - force a triple fault.. */
> load_idt(&no_idt);
> __asm__ __volatile__("int3");
> }
> }
> if (efi_enabled)
> efi.reset_system(EFI_RESET_WARM, EFI_SUCCESS, 0, NULL);
>
> machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
> }
>
> void machine_restart(char * __unused)
> {
> machine_shutdown();
> machine_emergency_restart();
> }
>
>
> If it does not, try this reboot=tc - this is closely resembles
> what you proposed in your mail (pseudo-patch):
>
> static int __init reboot_setup(char *str)
> {
> while(1) {
> switch (*str) {
> + case 't': /* "triple fault" reboot */
> + reboot_thru_bios = 2;
> + break;
> case 'w': /* "warm" reboot (no memory testing etc) */
> reboot_mode = 0x1234;
> break;
> ...
> void machine_emergency_restart(void)
> {
> + if (reboot_thru_bios == 2) {
> + *((unsigned short *)__va(0x472)) = reboot_mode;
> + load_idt(&no_idt);
> + __asm__ __volatile__("int3");
> + }
> if (!reboot_thru_bios) {
> if (efi_enabled) {
> efi.reset_system(EFI_RESET_COLD, EFI_SUCCESS, 0, NULL);
> --
> vda
I don't know how to make `reboot` or `init 0` take the required
parameters! I don't know how to get from user-mode into the kernel
code with any such parameters. I looked through `proc` and couldn't
find anything for such parameters either:
Script started on Mon 21 Nov 2005 12:42:11 PM EST
[root@chaos root]# reboot=cb
[root@chaos root]# strace reboot=cb
strace: reboot=cb: command not found
[root@chaos root]# strace reboot -cb
execve("/sbin/reboot", ["reboot", "-cb"], [/* 22 vars */]) = 0
uname({sys="Linux", node="chaos.analogic.com", ...}) = 0
brk(0) = 0x804b000
open("/etc/ld.so.preload", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0666, st_size=0, ...}) = 0
close(3) = 0
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=123802, ...}) = 0
old_mmap(NULL, 123802, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7f3e000
close(3) = 0
open("/lib/tls/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300{\230"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1455084, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f3d000
old_mmap(0x4a973000, 1158124, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4a973000
old_mmap(0x4aa88000, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x115000) = 0x4aa88000
old_mmap(0x4aa8c000, 7148, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4aa8c000
close(3) = 0
mprotect(0x4aa88000, 8192, PROT_READ) = 0
mprotect(0x4a96b000, 4096, PROT_READ) = 0
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7f3d540, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
munmap(0xb7f3e000, 123802) = 0
geteuid32() = 0
write(2, "usage: reboot [-n] [-w] [-d] [-f"..., 44usage: reboot [-n] [-w] [-d] [-f] [-i] [-p]
) = 44
write(2, "\t\t -n: don\'t sync before reboot"..., 47 -n: don't sync before rebooting the system
) = 47
write(2, "\t\t -w: only write a wtmp reboot"..., 50 -w: only write a wtmp reboot record and exit.
) = 50
write(2, "\t\t -d: don\'t write a wtmp recor"..., 35 -d: don't write a wtmp record.
) = 35
write(2, "\t\t -f: force halt/reboot, don\'t"..., 48 -f: force halt/reboot, don't call shutdown.
) = 48
write(2, "\t\t -p: power down the system (i"..., 62 -p: power down the system (if possible, otherwise reboot)
) = 62
exit_group(1) = ?
[root@chaos root]#
[root@chaos root]# exit
exit
Script done on Mon 21 Nov 2005 12:43:09 PM EST
`man reboot` doesn't show any parameters.
Cheers,
Dick Johnson
Penguin : Linux version 2.6.13.4 on an i686 machine (5589.52 BogoMips).
Warning : 98.36% of all statistics are fiction.
.
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