Re: Cannot boot the real thing from HDD

Marc-F. Lucca-Daniau
2020-01-24T21:05:50Z

Hello Paul,

I added some error checking with very simple traces in my latest commit:
https://github.com/jbruchon/elks/commit/63647a9a37ec3c5751fb2adc4ddad368e18ba7c5

It would be nice if you (or someone else on that mailing list) could try to boot again from a floppy disk and report the traces in case of any failure.

Also, I added some options to describe the HD geometry in the configuration, not to have to hack that part of code:
https://github.com/jbruchon/elks/commit/28d5f0ae66fd62bb7e25770e23d3c402cd301d76

And last but not least, the boot block now reuses the driver number as provided by the BIOS, again to avoid forcing it in the code:
https://github.com/jbruchon/elks/commit/9dbcd5ace60dc19f1bad24e34f1a3dd8793bcfcf

MFLD

Le 22/12/2019 à 11:51, Marc-F. Lucca-Daniau a écrit :
> Hello Paul,
>
> I forced the build of minix.bin to 8086 model (-mtune 8086), but no
> change in the binary, so not related to possible 80186/286 instructions.
>
> Also, you memory is largely enough for the relocation of the code, so
> not related either (it could fail for memory < 128 Kb).
>
> I am currently suspecting the INT 13h in disk_read() to fail at one
> moment, but as there is no error checking in load_zone() and in
> load_file() in the current version, it could be a silent error.
>
> I am going to try to add that error checking in the remaining space of
> the second sector.
>
> Stay tuned...
>
> MFLD
>
>
> Le 18/12/2019 à 23:51, Paul Osmialowski a écrit :
>> Some more info:
>>
>> CPU: 8088, no FPU installed (empty socket)
>> MEM: 640kB, no expansions
>> FDD: standard 765-based FDD controller on 8-bit ISA card
>> HDD: XT-CF IDE controller on 8-bit ISA card bought here:
>>
>> https://www.lo-tech.co.uk/wiki/Lo-tech_ISA_CompactFlash_Adapter_revision_2b
>>
>>
>> with BIOS obtained from here:
>>
>> https://code.google.com/archive/p/xtideuniversalbios
>>
>> On Wed, 18 Dec 2019, Paul Osmialowski wrote:
>>
>>> Hi Marc,
>>>
>>> Thanks for your quick reply. This machine is NOT an original IBM
>>> PC/XT, it
>>> is a cheap Taiwan made clone from 1986, very popular Turbo XT.
>>>
>>> Using simple Willem programmer I managed to dump its BIOS to a file
>>> (attached xt-rom.BIN file, 8192 bytes). When powered on it prints:
>>>
>>> T U R B O - XT 1986
>>> Speed 4.77/8.00MHz Version 3.10
>>>
>>> Thanks,
>>> Paul
>>>
>>> On Wed, 18 Dec 2019, Marc-François Lucca-Daniau wrote:
>>>
>>>> Hello Paul,
>>>>
>>>> I walked into the dump of your CF image, and everything looks
>>>> correct : Minix boot blocks, geometry constants, filesystem, root
>>>> directory and kernel image.
>>>>
>>>> Could you please tell me the size of your low memory, and confirm
>>>> the processor is a 8088/86, not a 80186/286 ? After reading the
>>>> code of the boot blocks again, I found two potential failures related.
>>>>
>>>> Also, if you could tell me the BIOS version & date, for me to have
>>>> a look in the IBM manual ?
>>>>
>>>> Thanks,
>>>>
>>>> MFLD
>>>>
>>>>
>>>> Le mar. 17 déc. 2019 23:21, Paul Osmialowski <pawelo@king.net.pl> a
>>>> écrit :
>>>>        Hi Marc,
>>>>
>>>>        The bzipped file is so small I'd try to attach it to this
>>>> message.
>>>>        The other attachment is the diff of all of my changes.
>>>>
>>>>        I must admit, I was looking into wrong places. As I mounted
>>>> this image, it
>>>>        indeed contains MINIX filesystem with /linux file in it, and
>>>> that file
>>>>        indeed has magic string "ELKS" at offset 0x1E6. So I
>>>> suspect, load_zone()
>>>>        does something wrong.
>>>>
>>>>        Note that I wasn't able to boot from 360k floppy either
>>>> (with the same
>>>>        outcome!), despite all the changes as in the patch.
>>>>
>>>>        Cheers,
>>>>        Paul
>>>>
>>>>        On Tue, 17 Dec 2019, Marc-F. Lucca-Daniau wrote:
>>>>
>>>>        > Hello Paul,
>>>>        >
>>>>        > I understand your mail on dec-16, but I don't the latest
>>>> today.
>>>>        >
>>>>        > * minix_second.c loads the root directory, then finds the
>>>> "/linux" file in it,
>>>>        > as you got the "Linux found!" trace.
>>>>        >
>>>>        > * the "linux" file is supposed to be the
>>>> /elks/arch/i86/boot/Image (see
>>>>        > image/Makefile):
>>>>        >
>>>>        > sudo install $(ELKS_DIR)/arch/i86/boot/Image
>>>> $(TARGET_MNT)/linux
>>>>        >
>>>>        > * that file concatenates 3 other files : bootsect, setup
>>>> and system (through
>>>>        > the /elks/arch/i86/tools utility)
>>>>        >
>>>>        > * run_prog() checks that the "bootsect" file contains
>>>> "ELKS" at offset 1E6h:
>>>>        >
>>>>        > minix_first.S:
>>>>        >     mov 0x01E6,%ax  // check for ELKS magic number
>>>>        >     cmp $0x4C45,%ax
>>>>        >     jnz not_elks
>>>>        >     mov 0x01E8,%ax
>>>>        >     cmp $0x534B,%ax
>>>>        >     jz  boot_it
>>>>        >
>>>>        > bootsect.S:
>>>>        > .org 0x1E3
>>>>        > msg1:
>>>>        >     .byte 13,10,7
>>>>        >     .ascii "ELKS Boot"
>>>>        >
>>>>        > * dumping the "Image" file on my machine shows that the
>>>> offset and the string
>>>>        > are correct:
>>>>        >
>>>>        > 0001e0 12 0f 09 0d 0a 07 45 4c 4b 53 20 42 6f 6f 74 20
>>>> >......ELKS Boot <
>>>>        >
>>>>        > * so I agree that the loaded file "linux" is not the right
>>>> one in memory
>>>>        >
>>>>        > Could you please:
>>>>        >
>>>>        > 1) dump the "Image" file and check the data @ 1E0h ?
>>>>        >
>>>>        > 2) "DD" the content of your CF card to a file and upload
>>>> that file to a
>>>>        > server, so that I could inspect the actual structure of
>>>> the Minix filesystem
>>>>        > on your CF card ? I understood you flashed it with
>>>> fd1440.bin, but I would
>>>>        > like to see what the CF card contains at the end.
>>>>        >
>>>>        > Thanks,
>>>>        >
>>>>        > MFLD
>>>>        >
>>>>        >
>>>>        >
>>>>        >
>>>>        > Le 17/12/2019 ? 11:23, Paul Osmialowski a écrit :
>>>>        > > I've looked at the problem more closely and now I see
>>>> that after
>>>>        > > "Revise bootblocks for GCC-IA16" commit
>>>>        > > (9e038b816014f83c0808df1ee5697380cd6be499) there's no
>>>> way to boot ELKS on
>>>>        > > any real machine whatsoever. The magic number was
>>>> specified in file
>>>>        > > sysboot16.s that this patch hapily removes. The
>>>> bootloader's run_prog()
>>>>        > > routine looks for non-existing thing. And even after
>>>> removal of that check,
>>>>        > > the bootloader stucks somewhere after boot_it label. It
>>>> happens with hd,
>>>>        > > it happens with floppy. ELKS now can be used only with
>>>> emulators and it's
>>>>        > > a regression comparing to what was possible last year.
>>>>        > >
>>>>        > > On Mon, 16 Dec 2019, Paul Osmialowski wrote:
>>>>        > >
>>>>        > > > Hello MFLD,
>>>>        > > >
>>>>        > > > As I'm back to my old flat for a while, I can follow
>>>> this up for couple of
>>>>        > > > days.
>>>>        > > >
>>>>        > > > I've made following changes in bootsector files:
>>>>        > > >
>>>>        > > > diff --git a/elkscmd/bootblocks/minix_first.S
>>>>        > > > b/elkscmd/bootblocks/minix_first.S
>>>>        > > > index c70625a6..cce72ba1 100644
>>>>        > > > --- a/elkscmd/bootblocks/minix_first.S
>>>>        > > > +++ b/elkscmd/bootblocks/minix_first.S
>>>>        > > > @@ -75,7 +75,8 @@ loopy:
>>>>        > > >          mov $0x0201,%ax    // read 1 sector
>>>>        > > >          mov $sector_2,%bx  // destination
>>>>        > > >          mov $2,%cx         // track 0 - from sector 2
>>>> (base 1)
>>>>        > > > -       xor %dx,%dx        // drive 0 - head 0
>>>>        > > > +       mov $0x80,%dx      // head 0 - drive 0x80
>>>>        > > > +       // xor %dx,%dx        // drive 0 - head 0
>>>>        > > >          int $0x13          // BIOS disk services
>>>>        > > >          jc loopy
>>>>        > > >          jmp _next2
>>>>        > > > @@ -250,7 +251,7 @@ drive_reset:
>>>>        > > >   // #undef CONFIG_IMG_FD360
>>>>        > > >     sect_max:
>>>>        > > > -#ifdef CONFIG_IMG_FD720
>>>>        > > > +#if defined(CONFIG_IMG_FD360) ||
>>>> defined(CONFIG_IMG_FD720)
>>>>        > > >          .word 9
>>>>        > > >   #endif
>>>>        > > >   #if defined(CONFIG_IMG_FD1200)
>>>>        > > > @@ -262,11 +263,17 @@ sect_max:
>>>>        > > >   #if defined(CONFIG_IMG_FD1680)
>>>>        > > >          .word 21
>>>>        > > >   #endif
>>>>        > > > +#if defined(CONFIG_IMG_HD)
>>>>        > > > +       .word 61
>>>>        > > > +#endif
>>>>        > > >     head_max:
>>>>        > > >   #if defined(CONFIG_IMG_FD1440) ||
>>>> defined(CONFIG_IMG_FD720) ||
>>>>        > > > defined(CONFIG_IMG_FD360) ||
>>>> defined(CONFIG_IMG_FD1200) ||
>>>>        > > > defined(CONFIG_IMG_FD1680)
>>>>        > > >          .word 2
>>>>        > > >   #endif
>>>>        > > > +#if defined(CONFIG_IMG_HD)
>>>>        > > > +       .word 1
>>>>        > > > +#endif
>>>>        > > >     track_max:
>>>>        > > >   #if defined(CONFIG_IMG_FD360)
>>>>        > > > @@ -275,6 +282,9 @@ track_max:
>>>>        > > >   #if defined(CONFIG_IMG_FD1440) ||
>>>> defined(CONFIG_IMG_FD720)
>>>>        > > >          .word 80
>>>>        > > >   #endif
>>>>        > > > +#if defined(CONFIG_IMG_HD)
>>>>        > > > +       .word 1024
>>>>        > > > +#endif
>>>>        > > >
>>>>  //------------------------------------------------------------------------------
>>>>        > > >   diff --git a/elkscmd/bootblocks/minix_second.c
>>>>        > > > b/elkscmd/bootblocks/minix_second.c
>>>>        > > > index f33c6139..9fd3e6d2 100644
>>>>        > > > --- a/elkscmd/bootblocks/minix_second.c
>>>>        > > > +++ b/elkscmd/bootblocks/minix_second.c
>>>>        > > > @@ -74,7 +74,7 @@ static int load_super ()
>>>>        > > >          int err;
>>>>        > > >            while (1) {
>>>>        > > > -               err = disk_read (0, 2, 2, sb_block,
>>>> seg_data ());
>>>>        > > > +               err = disk_read (0x80, 2, 2, sb_block,
>>>> seg_data ());
>>>>        > > >                  //if (err) break;
>>>>        > > >                    sb_data = (struct super_block *)
>>>> sb_block;
>>>>        > > > @@ -116,7 +116,7 @@ static int load_inode ()
>>>>        > > >                  // Compute inode block and load if
>>>> not cached
>>>>        > > >                    int ib = ib_first + i_now /
>>>> INODES_PER_BLOCK;
>>>>        > > > -               err = disk_read (0, ib << 1, 2,
>>>> i_block, seg_data ());
>>>>        > > > +               err = disk_read (0x80, ib << 1, 2,
>>>> i_block, seg_data ());
>>>>        > > >                  //if (err) break;
>>>>        > > >                    // Get inode data
>>>>        > > > @@ -137,12 +137,12 @@ static int load_zone (int level,
>>>> zone_nr * z_start,
>>>>        > > > zone_nr * z_end)
>>>>        > > >          for (zone_nr * z = z_start; z < z_end; z++) {
>>>>        > > >                  if (level == 0) {
>>>>        > > >                          // FIXME: image can be > 64K
>>>>        > > > -                       err = disk_read (0, (*z) << 1,
>>>> 2, i_now ? f_pos :
>>>>        > > > d_dir + f_pos, i_now ? LOADSEG : seg_data ());
>>>>        > > > +                       err = disk_read (0x80, (*z) <<
>>>> 1, 2, i_now ? f_pos
>>>>        > > > : d_dir + f_pos, i_now ? LOADSEG : seg_data ());
>>>>        > > >                          f_pos += BLOCK_SIZE;
>>>>        > > >                          if (f_pos >= i_data->i_size)
>>>> break;
>>>>        > > >                  } else {
>>>>        > > >                          int next = level - 1;
>>>>        > > > -                       err = disk_read (0, *z << 1,
>>>> 2, z_block [next],
>>>>        > > > seg_data ());
>>>>        > > > +                       err = disk_read (0x80, *z <<
>>>> 1, 2, z_block [next],
>>>>        > > > seg_data ());
>>>>        > > >                          load_zone (next, (zone_nr *)
>>>> z_block [next],
>>>>        > > > (zone_nr *) (z_block [next] + BLOCK_SIZE));
>>>>        > > >                  }
>>>>        > > >          }
>>>>        > > > @@ -227,7 +227,7 @@ void main ()
>>>>        > > >                    for (int d = 0; d < i_data->i_size;
>>>> d += DIRENT_SIZE) {
>>>>        > > >                          if (!strcmp (d_dir + 2 + d,
>>>> "linux")) {
>>>>        > > > -                               //puts ("Linux
>>>> found\r\n");
>>>>        > > > +                               puts ("Linux found\r\n");
>>>>        > > >                                  i_now = (*(int
>>>> *)(d_dir + d)) - 1;
>>>>        > > > load_file ();
>>>>        > > > run_prog ();
>>>>        > > >
>>>>        > > > Summary is following:
>>>>        > > >
>>>>        > > > - added missing check for CONFIG_IMG_FD360
>>>> (definitely, should be fixed
>>>>        > > > upstream too!)
>>>>        > > > - hardcoded HD C/H/S geometry with values outputed by
>>>> 'fdisk -c=dos' :
>>>>        > > > 1024/1/61 (~32MB CF card)
>>>>        > > > - "Linux found" is printed when certain point in
>>>> main() is reached (helps
>>>>        > > > with investigation)
>>>>        > > > - Disk drive is ensured 0x80 wherever I've managed to
>>>> find it should be
>>>>        > > > hardcoded.
>>>>        > > >
>>>>        > > > Result:
>>>>        > > >
>>>>        > > > MINIX boot
>>>>        > > > Linux found
>>>>        > > > Not ELKS!
>>>>        > > >
>>>>        > > > So it seems we have a small progress comparing to last
>>>> attempt: sector 2
>>>>        > > > is read, main() gets executed, and run_prog() gets
>>>> called. Yet run_prog()
>>>>        > > > finds that what was read from storage wasn't the thing
>>>> that was expected
>>>>        > > > (does it look for "EL" at the right offset?!). I
>>>> suspect something went
>>>>        > > > wrong with load_file(). Any hints welcomed.
>>>>        > > >
>>>>        > > > Thanks,
>>>>        > > > Paul
>>>>        > > >
>>>>        > > > On Sun, 21 Apr 2019, Marc-F. Lucca-Daniau wrote:
>>>>        > > >
>>>>        > > > > Hello Paul,
>>>>        > > > >
>>>>        > > > > Yes, all your testing is consistent, and really help
>>>> to know where to
>>>>        > > > > improve
>>>>        > > > > the ELKS boot for real HW. Thanks for that !
>>>>        > > > >
>>>>        > > > > Let us plan that improvement for the next commits...
>>>>        > > > >
>>>>        > > > > Thanks,
>>>>        > > > >
>>>>        > > > > MFLD
>>>>        > > > >
>>>>        > > > >
>>>>        > > > > Le 18/04/2019 ? 13:48, Paul Osmialowski a écrit :
>>>>        > > > > > Hello,
>>>>        > > > > >
>>>>        > > > > > Booting fd1140.bin from CF card didn't help, from
>>>> visible point of
>>>>        > > > > > view,
>>>>        > > > > > I'm observing the same behaviour, "MINIX boot" on
>>>> screen and FDD led
>>>>        > > > > > blinking.
>>>>        > > > > >
>>>>        > > > > > I also did some confirmation test and changed mov
>>>> $0x80,%dx back to
>>>>        > > > > > xor
>>>>        > > > > > %dx,%dx and indeed, "Sector 2!" appeared again
>>>> (with FDD led
>>>>        > > > > > blinking), so
>>>>        > > > > > at least symptoms are consistent. There must be
>>>> something FDD-bound
>>>>        > > > > > between sector_2 and disk_read(0x80,...) calls in
>>>> minix_second.c.
>>>>        > > > > >
>>>>        > > > > > On Thu, 18 Apr 2019, Marc-F. Lucca-Daniau wrote:
>>>>        > > > > >
>>>>        > > > > > > Hello,
>>>>        > > > > > >
>>>>        > > > > > > For a "flat volume", please DD the 'fd1440.bin'
>>>> on your CF, don't
>>>>        > > > > > > use the
>>>>        > > > > > > 'HD'
>>>>        > > > > > > image & option, I added it to the ELKS
>>>> configuration, but it is not
>>>>        > > > > > > completed
>>>>        > > > > > > & tested (see issue #199).
>>>>        > > > > > >
>>>>        > > > > > > Thanks,
>>>>        > > > > > >
>>>>        > > > > > > MFLD
>>>>        > > > > > >
>>>>        > > > > > >
>>>>        > > > > > > Le 17/04/2019 ? 23:12, Paul Osmialowski a écrit :
>>>>        > > > > > > > Hi Marc,
>>>>        > > > > > > >
>>>>        > > > > > > > So I changed minix_first.S as such:
>>>>        > > > > > > >
>>>>        > > > > > > > @@ -68,7 +68,7 @@ _next1:
>>>>        > > > > > > >            mov $0x0201,%ax    // read 1 sector
>>>>        > > > > > > >            mov $sector_2,%bx  // destination
>>>>        > > > > > > >            mov $2,%cx         // track 0 -
>>>> from sector 2 (base 1)
>>>>        > > > > > > > -       xor %dx,%dx        // drive 0 - head 0
>>>>        > > > > > > > +       mov $0x80,%dx      // head 0 - drive 0x80
>>>>        > > > > > > >            int $0x13          // BIOS disk
>>>> services
>>>>        > > > > > > >            jnc _next2
>>>>        > > > > > > >
>>>>        > > > > > > > And placed hd.img directly to /dev/hda (so now
>>>> there's no
>>>>        > > > > > > > partition
>>>>        > > > > > > > table,
>>>>        > > > > > > > and no MBR written by FreeDOS). Now, "MINIX
>>>> boot" appears on
>>>>        > > > > > > > screen,
>>>>        > > > > > > > which
>>>>        > > > > > > > is a good sign, but, FDD led is blinking and
>>>> nothing else happens,
>>>>        > > > > > > > Ctrl-Alt-Del doesn't reboot, power-off is the
>>>> only option.
>>>>        > > > > > > > Something
>>>>        > > > > > > > else
>>>>        > > > > > > > in between sector_2 and minix_second.c is
>>>> hard-coded for trying to
>>>>        > > > > > > > access
>>>>        > > > > > > > FDD...
>>>>        > > > > > > >
>>>>        > > > > > > > On Wed, 17 Apr 2019, Marc-F. Lucca-Daniau wrote:
>>>>        > > > > > > >
>>>>        > > > > > > > > Hello Paul,
>>>>        > > > > > > > >
>>>>        > > > > > > > > I should have asked that question before all
>>>> : is your CF card
>>>>        > > > > > > > > partitioned
>>>>        > > > > > > > > ?
>>>>        > > > > > > > >
>>>>        > > > > > > > > In the boot sector, the 'disk_read'
>>>> procedure computes the CHS
>>>>        > > > > > > > > for the
>>>>        > > > > > > > > BIOS
>>>>        > > > > > > > > routines from the absolute sector number.
>>>>        > > > > > > > >
>>>>        > > > > > > > > But today that procedure does not offset
>>>> that number based on
>>>>        > > > > > > > > the
>>>>        > > > > > > > > partition
>>>>        > > > > > > > > absolute first sector (it is planned for
>>>> issue #199).
>>>>        > > > > > > > >
>>>>        > > > > > > > > So it cannot work on a partitioned disk,
>>>> because even if you
>>>>        > > > > > > > > force the
>>>>        > > > > > > > > drive
>>>>        > > > > > > > > number to 0x80, and succeed to load the
>>>> second sector (the MINIX
>>>>        > > > > > > > > boot
>>>>        > > > > > > > > loader
>>>>        > > > > > > > > in C), the 'disk_read' procedure won't
>>>> offset the relative
>>>>        > > > > > > > > sector
>>>>        > > > > > > > > numbers
>>>>        > > > > > > > > given by the C code, and the parsing of the
>>>> file system will
>>>>        > > > > > > > > fail
>>>>        > > > > > > > > after
>>>>        > > > > > > > > some
>>>>        > > > > > > > > times.
>>>>        > > > > > > > >
>>>>        > > > > > > > > Maybe a more simple test with a single
>>>> volume on your CF card,
>>>>        > > > > > > > > before
>>>>        > > > > > > > > improving the procedure to support
>>>> partitioning ?
>>>>        > > > > > > > >
>>>>        > > > > > > > > Thank you for your testing !
>>>>        > > > > > > > >
>>>>        > > > > > > > > MFLD
>>>>        > > > > > > > >
>>>>        > > > > > > > >
>>>>        > > > > > > > > Le 16/04/2019 ? 23:18, Paul Osmialowski a
>>>> écrit :
>>>>        > > > > > > > > > Hi Marc,
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > Thanks for the hints. Feels like
>>>> disk-bootable ELKS is getting
>>>>        > > > > > > > > > closer,
>>>>        > > > > > > > > > but
>>>>        > > > > > > > > > we're still not there yet. I've changed
>>>> first param of all
>>>>        > > > > > > > > > occurrences
>>>>        > > > > > > > > > of
>>>>        > > > > > > > > > disk_read in minix_second.c to 0x80,
>>>> unfortunately, it still
>>>>        > > > > > > > > > behaves
>>>>        > > > > > > > > > the
>>>>        > > > > > > > > > same way: as "MINIX boot" is displayed,
>>>> the led on the first
>>>>        > > > > > > > > > FDD
>>>>        > > > > > > > > > blinks
>>>>        > > > > > > > > > and nothing happens, "Sector 2!" and
>>>> "Press key" pops up
>>>>        > > > > > > > > > again. I
>>>>        > > > > > > > > > guess
>>>>        > > > > > > > > > this is the reason (in minix_first.S):
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > _next1:
>>>>        > > > > > > > > >
>>>>        > > > > > > > > >    mov $msg_head,%bx
>>>>        > > > > > > > > >    call _puts
>>>>        > > > > > > > > >
>>>>        > > > > > > > > >    // Load the second sector of the boot
>>>> block
>>>>        > > > > > > > > >
>>>>        > > > > > > > > >    mov $0x0201,%ax    // read 1 sector
>>>>        > > > > > > > > >    mov $sector_2,%bx  // destination
>>>>        > > > > > > > > >    mov $2,%cx         // track 0 - from
>>>> sector 2
>>>>        > > > > > > > > > (base 1)
>>>>        > > > > > > > > >    xor %dx,%dx        // drive 0 - head 0
>>>>        > > > > > > > > >    int $0x13          // BIOS disk services
>>>>        > > > > > > > > >    jnc _next2
>>>>        > > > > > > > > >             mov $msg_load,%bx
>>>>        > > > > > > > > >    call _puts
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > // void reboot ()
>>>>        > > > > > > > > >
>>>>        > > > > > > > > >    .global reboot
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > reboot:
>>>>        > > > > > > > > >
>>>>        > > > > > > > > >    mov $msg_reboot,%bx
>>>>        > > > > > > > > >    call _puts
>>>>        > > > > > > > > >    xor %ax,%ax  // wait for key
>>>>        > > > > > > > > >    int $0x16
>>>>        > > > > > > > > >    int $0x19
>>>>        > > > > > > > > >    jmp reboot
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > I tried to make some changes to it. Note
>>>> that now I'm using
>>>>        > > > > > > > > > 32MB CF
>>>>        > > > > > > > > > card
>>>>        > > > > > > > > > with geometry 60 tracks per head, 16
>>>> heads, 63 sectors per
>>>>        > > > > > > > > > track.
>>>>        > > > > > > > > > Using
>>>>        > > > > > > > > > hexviewer I've found that the boot
>>>> partition starts at byte
>>>>        > > > > > > > > > 0x7e00
>>>>        > > > > > > > > > on the CF card (first sector of the second
>>>> track), so sector_2
>>>>        > > > > > > > > > is at
>>>>        > > > > > > > > > byte
>>>>        > > > > > > > > > 0x8000 on the CF card (assuming that the
>>>> thing I should look
>>>>        > > > > > > > > > for is
>>>>        > > > > > > > > > the
>>>>        > > > > > > > > > same as I can find at byte 512 of hd.img).
>>>> So I modified
>>>>        > > > > > > > > > minix_first.S
>>>>        > > > > > > > > > as
>>>>        > > > > > > > > > such:
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > -  mov $2,%cx         // track 0 - from
>>>> sector 2 (base 1)
>>>>        > > > > > > > > > -  xor %dx,%dx        // drive 0 - head 0
>>>>        > > > > > > > > > +  mov $0x42,%cx      // track 1 - from
>>>> sector 2 (base 1)
>>>>        > > > > > > > > > +  mov $0x80,%dx      // head 0 - drive 0x80
>>>>        > > > > > > > > > (CX: assuming 6 bits for sector, track 1
>>>> should be 0x40)
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > Unfortunately, the only real change is
>>>> that FDD does not blink
>>>>        > > > > > > > > > anymore.
>>>>        > > > > > > > > > After a longer while of waiting "Secotr
>>>> 2!" and "Press key"
>>>>        > > > > > > > > > still
>>>>        > > > > > > > > > pops
>>>>        > > > > > > > > > out.
>>>>        > > > > > > > > >
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > On Tue, 16 Apr 2019, Marc-F. Lucca-Daniau
>>>> wrote:
>>>>        > > > > > > > > >
>>>>        > > > > > > > > > > Hello Paul,
>>>>        > > > > > > > > > >
>>>>        > > > > > > > > > > Sounds good, because if you see "MINIX
>>>> boot" message when
>>>>        > > > > > > > > > > booting
>>>>        > > > > > > > > > > from
>>>>        > > > > > > > > > > your
>>>>        > > > > > > > > > > HD/CF, and if you can mount it when
>>>> booting from the floppy,
>>>>        > > > > > > > > > > it
>>>>        > > > > > > > > > > means
>>>>        > > > > > > > > > > there
>>>>        > > > > > > > > > > are only a few changes left to make it
>>>> fully working.
>>>>        > > > > > > > > > >
>>>>        > > > > > > > > > > Did you tried to hack the 3 variables
>>>> 'sect_max', 'head_max'
>>>>        > > > > > > > > > > and
>>>>        > > > > > > > > > > 'track_max'
>>>>        > > > > > > > > > > in 'elkscmd/bootblocks/minix_first.S'
>>>> with the geometry as
>>>>        > > > > > > > > > > presented
>>>>        > > > > > > > > > > by
>>>>        > > > > > > > > > > your
>>>>        > > > > > > > > > > adapter (123 / 16 / 6) ?
>>>>        > > > > > > > > > >
>>>>        > > > > > > > > > > Also, in
>>>> 'elkscmd/bootblocks/minix_second.c', the boot drive
>>>>        > > > > > > > > > > number is
>>>>        > > > > > > > > > > forced
>>>>        > > > > > > > > > > to 0 when calling 'disk_read' (as first
>>>> argument), so the
>>>>        > > > > > > > > > > MINIX
>>>>        > > > > > > > > > > boot
>>>>        > > > > > > > > > > loader
>>>>        > > > > > > > > > > has to be improved to use the right one
>>>> provided by the
>>>>        > > > > > > > > > > BIOS.
>>>>        > > > > > > > > > > Meantime,
>>>>        > > > > > > > > > > you
>>>>        > > > > > > > > > > can also hack that file and set that
>>>> argument to 0x80 (=
>>>>        > > > > > > > > > > first
>>>>        > > > > > > > > > > hard
>>>>        > > > > > > > > > > drive)
>>>>        > > > > > > > > > > for
>>>>        > > > > > > > > > > you experiment.
>>>>        > > > > > > > > > >
>>>>        > > > > > > > > > > MFLD
>>>>        > > > > > > > > > >
>>>>        > > > > > > > > > >
>>>>        > > > > > > > > > > Le 15/04/2019 ? 18:12, Paul Osmialowski
>>>> a écrit :
>>>>        > > > > > > > > > > > Just one more observation. I managed
>>>> to mount minix
>>>>        > > > > > > > > > > > filesystem
>>>>        > > > > > > > > > > > from
>>>>        > > > > > > > > > > > CF
>>>>        > > > > > > > > > > > Card on system booted from 360k
>>>> floppy! And not using
>>>>        > > > > > > > > > > > directhd
>>>>        > > > > > > > > > > > driver at
>>>>        > > > > > > > > > > > all! My mistake was, I tried to mount
>>>> /dev/hda1 while the
>>>>        > > > > > > > > > > > partition
>>>>        > > > > > > > > > > > is
>>>>        > > > > > > > > > > > at
>>>>        > > > > > > > > > > > /dev/bda1
>>>>        > > > > > > > > > > >
>>>>        > > > > > > > > > > > I've noticed, chroot command would be
>>>> a great help.
>>>>        > > > > > > > > > > >
>>>>        > > > > > > > > > > > Cheers again,
>>>>        > > > > > > > > > > > Paul
>>>>        > > > > > > > > > > >
>>>>        > > > > > > > > > > > On Mon, 15 Apr 2019, Paul Osmialowski
>>>> wrote:
>>>>        > > > > > > > > > > >
>>>>        > > > > > > > > > > > > Hi Marc,
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > Thanks for your response. I've
>>>> noticed a few interesting
>>>>        > > > > > > > > > > > > things
>>>>        > > > > > > > > > > > > btw.
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > I've found lots of #ifdef HARDDISK
>>>> in this new boot
>>>>        > > > > > > > > > > > > sector
>>>>        > > > > > > > > > > > > code,
>>>>        > > > > > > > > > > > > so I
>>>>        > > > > > > > > > > > > decided to give it a try. I've
>>>> placed this boot sector
>>>>        > > > > > > > > > > > > code in
>>>>        > > > > > > > > > > > > /dev/hda1 (leaving original FreeDOS
>>>> MBR in /dev/hda) and
>>>>        > > > > > > > > > > > > for a
>>>>        > > > > > > > > > > > > first
>>>>        > > > > > > > > > > > > time
>>>>        > > > > > > > > > > > > I've noticed something is alive:
>>>> "MINIX boot" appeared
>>>>        > > > > > > > > > > > > on
>>>>        > > > > > > > > > > > > screen
>>>>        > > > > > > > > > > > > when
>>>>        > > > > > > > > > > > > I
>>>>        > > > > > > > > > > > > booted from CF Card! But that's all,
>>>> the next thing it
>>>>        > > > > > > > > > > > > tried
>>>>        > > > > > > > > > > > > to do
>>>>        > > > > > > > > > > > > was
>>>>        > > > > > > > > > > > > to
>>>>        > > > > > > > > > > > > access floppy disk drive, having it
>>>> empty, I could only
>>>>        > > > > > > > > > > > > see
>>>>        > > > > > > > > > > > > "Press
>>>>        > > > > > > > > > > > > key"
>>>>        > > > > > > > > > > > > and it rebooted itself after
>>>> pressing any key. I guess
>>>>        > > > > > > > > > > > > my
>>>>        > > > > > > > > > > > > XT-IDE
>>>>        > > > > > > > > > > > > card
>>>>        > > > > > > > > > > > > is
>>>>        > > > > > > > > > > > > not handled properly, although when
>>>> I boot ELKS from
>>>>        > > > > > > > > > > > > floppy I
>>>>        > > > > > > > > > > > > can
>>>>        > > > > > > > > > > > > see
>>>>        > > > > > > > > > > > > this
>>>>        > > > > > > > > > > > > on the serial console:
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > hd Driver Copyright (C) 1994
>>>> Yggdrasil Computing, Inc.
>>>>        > > > > > > > > > > > >
>>>>                      Extended
>>>>        > > > > > > > > > > > > and modified for Liux 8086 by Alan Cox.
>>>>        > > > > > > > > > > > >
>>>>     doshd:
>>>>        > > > > > > > > > > > > 2 floppy drives and 1 hard drive
>>>>        > > > > > > > > > > > >
>>>>                                            /dev/hda:
>>>>        > > > > > > > > > > > > 123 cylindrs, 16 heads, 6 sectors =
>>>> 60.5 Mb
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > (that's when 64MB FreeDOS CF Card is
>>>> inserted)
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > Also, before the ELKS boot starts I
>>>> can see this:
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > XTIDE Universal BIOS (XT) @ C800h
>>>>        > > > > > > > > > > > > Master at 300h: CF Card
>>>>        > > > > > > > > > > > > Slave  at 300h: not found
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > I've tried to compile directhd
>>>> driver, but it lacks
>>>>        > > > > > > > > > > > > #include
>>>>        > > > > > > > > > > > > <arch/io.h>
>>>>        > > > > > > > > > > > > causing link-time issue as some of
>>>> the macros defined
>>>>        > > > > > > > > > > > > there
>>>>        > > > > > > > > > > > > are
>>>>        > > > > > > > > > > > > mistaken
>>>>        > > > > > > > > > > > > for functions (outb_p() and
>>>> friends), adding missing
>>>>        > > > > > > > > > > > > #include
>>>>        > > > > > > > > > > > > <arch/io.h>
>>>>        > > > > > > > > > > > > makes whole thing buildable, yet it
>>>> still doesn't seem
>>>>        > > > > > > > > > > > > to make
>>>>        > > > > > > > > > > > > any
>>>>        > > > > > > > > > > > > (visible) difference.
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > Cheers,
>>>>        > > > > > > > > > > > > Paul
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > On Sun, 14 Apr 2019, Marc-F.
>>>> Lucca-Daniau wrote:
>>>>        > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > Hello,
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > Not a surprise, as the new code
>>>> has only been tested
>>>>        > > > > > > > > > > > > > on 1.44
>>>>        > > > > > > > > > > > > > MB
>>>>        > > > > > > > > > > > > > floppy.
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > Looks like there is a missing
>>>> "#ifdef FD360" in the
>>>>        > > > > > > > > > > > > > boot
>>>>        > > > > > > > > > > > > > sector
>>>>        > > > > > > > > > > > > > new
>>>>        > > > > > > > > > > > > > code...
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > Now tracked by issue
>>>>        > > > > > > > > > > > > >
>>>> https://github.com/jbruchon/elks/issues/253
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > Thanks for the report,
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > MFLD
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > Le 14/04/2019 ? 19:46, Paul
>>>> Osmialowski a écrit :
>>>>        > > > > > > > > > > > > > > Hi,
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > > I'm having access to my old XT
>>>> for next couple of
>>>>        > > > > > > > > > > > > > > days so
>>>>        > > > > > > > > > > > > > > I
>>>>        > > > > > > > > > > > > > > decided to
>>>>        > > > > > > > > > > > > > > give the latest ELKS a go. Since
>>>> I still don't know
>>>>        > > > > > > > > > > > > > > how to
>>>>        > > > > > > > > > > > > > > boot it
>>>>        > > > > > > > > > > > > > > from
>>>>        > > > > > > > > > > > > > > CF-IDE card (I can boot FreeDOS
>>>> from it), I'm still
>>>>        > > > > > > > > > > > > > > booting it
>>>>        > > > > > > > > > > > > > > from
>>>>        > > > > > > > > > > > > > > 360k
>>>>        > > > > > > > > > > > > > > floppy. Unfortunately, nowadays
>>>> it only prints MINIX
>>>>        > > > > > > > > > > > > > > and
>>>>        > > > > > > > > > > > > > > reboots
>>>>        > > > > > > > > > > > > > > itself
>>>>        > > > > > > > > > > > > > > after a while.
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > > I managed to make it boot again
>>>> after reverting
>>>>        > > > > > > > > > > > > > > following
>>>>        > > > > > > > > > > > > > > commits
>>>>        > > > > > > > > > > > > > > on
>>>>        > > > > > > > > > > > > > > master:
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > >
>>>> 93b57f474cb0e3fa9917b4783781cd405c944b04 [libc] Data
>>>>        > > > > > > > > > > > > > > segment
>>>>        > > > > > > > > > > > > > > starts
>>>>        > > > > > > > > > > > > > > with
>>>>        > > > > > > > > > > > > > > nil data
>>>>        > > > > > > > > > > > > > >
>>>> 9e038b816014f83c0808df1ee5697380cd6be499 Revise
>>>>        > > > > > > > > > > > > > > bootblocks
>>>>        > > > > > > > > > > > > > > for
>>>>        > > > > > > > > > > > > > > GCC-IA16
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > > (the first one is reverted
>>>> mostrly to reduce
>>>>        > > > > > > > > > > > > > > conflicts
>>>>        > > > > > > > > > > > > > > when
>>>>        > > > > > > > > > > > > > > reverting
>>>>        > > > > > > > > > > > > > > the
>>>>        > > > > > > > > > > > > > > other one).
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > > I guess something went wrong
>>>> with implementing new
>>>>        > > > > > > > > > > > > > > features.
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > > Cheers,
>>>>        > > > > > > > > > > > > > > Paul
>>>>        > > > > > > > > > > > > > >
>>>>        > > > > > > > > > > > > > >
>>>>        >
>>>>
>>>>