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...boot fail */ #ifdef DEBUG_MARKER1 .macro ASCII_MARKER1 s:vararg .ascii \s .endm #else /* DEBUG_MARKER1 */ .macro ASCII_MARKER1 s:vararg .endm #endif /* DEBUG_MARKER1 */ #ifdef DEBUG_LOADE .macro LOADE r:req, t:req movw (e_\r), %\t .endm #else /* DEBUG_LOADE */ .macro LOADE r:req, t:req popw %\t .endm #endif /* DEBUG_LOADE */ .code16 .text entry = 0x7c00 stack = (entry) e0_ax = (stack-2) e0_cx = (stack-4) e0_dx = (stack-6) e0_bx = (stack-8) e0_sp = (stack-10) e0_bp = (stack-12) e0_si = (stack-14) e0_di = (stack-16) e0_bot = (stack-16) e_di = (e0_bot-2) /* Original regi...

...\ (read_sector_cbios) - jmp 1f + +#ifdef DEBUG_PRINT + push %si + call print_string + .ascii "E\r\n" + jmp 2f 1: + push %si + call print_string + .ascii "C\r\n" +2: + call print_string + .ascii "Key?\r\n" + pop %si + xor %ax, %ax + int $0x16 +#else +1: +#endif + popw %dx pushw %cx /* EBIOS flag */ /* Get (C)HS geometry */ movb $0x08, %ah int $0x13 + + /* here we computer CHS values or just do some dummy computation for EBIOS */ andw $0x3f, %cx /* Sector count */ popw %bx /* EBIOS flag */ pushw %cx /* -16: Save sectors on the stack */ @@ -223...

...D */ + + /* prepare to read sector size */ + sub $0x1c, %sp /* -28(%bp) == %sp */ + pushw $0x1e /* -30(%bp) == %sp */ + movw $0x200, -6(%bp) /* -6(%bp) sector size */ /* Check to see if we have EBIOS */ pushw %dx /* drive number */ @@ -86,6 +92,7 @@ next: xorb %dh, %dh stc int $0x13 + popw %dx /* restore drive */ jc 1f cmpw $0xaa55, %bx jne 1f @@ -97,22 +104,32 @@ next: movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ (read_sector_cbios) -1: - popw %dx + /* + * read sector size. + * Should not fail but if it does I assume that at least + * previous 5...

This patches add support for dynamic sectors to GPT MBR code. First 3 patches are trick and optimizations to gain some space for the forth patch. I have a modified version of SeaBIOS, some code and some script o test it I'll send on a different mail.

...x55aa, %bx xorw %cx, %cx xorb %dh, %dh @@ -167,20 +167,22 @@ next: read_sector_cbios: movb $0x42, %ah ; jmp read_common */ movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), (read_sector_cbios) - jmp 1f + jmp 2f 1: + xor %cx, %cx /* Clear EBIOS flag. */ +2: popw %dx pushw %cx /* EBIOS flag */ /* Get (C)HS geometry */ movb $0x08, %ah int $0x13 - andw $0x3f, %cx /* Sector count */ popw %bx /* EBIOS flag */ - pushw %cx /* -16: Save sectors on the stack */ movzbw %dh, %ax /* dh = max head */ incw %ax /...

...git a/mbr/gptmbr.S b/mbr/gptmbr.S > index 8ab6b50..7d98aee 100644 > --- a/mbr/gptmbr.S > +++ b/mbr/gptmbr.S > @@ -213,7 +213,7 @@ found_part: > > movzwl %cx,%eax /* Length of GPT entry */ > stosl > - > + > rep; movsb /* GPT entry follows MBR entry */ > popw %si > The removal of that trailing tab character is valid change. What is needed to get the patch applied in the leading git repository? Groeten Geert Stappers -- Leven en laten leven

...: + /* convert drive-number to two hex characters and insert them into the boot message */ + movw (drive_number), %dx + pushw %dx /* preserve for use by calculate_geometry */ + movw $msg_drive_number, %di + movb $0x02, %cl /* write two nibbles */ + call write_hex_value + +calculate_geometry: + popw %dx /* retrieve drive number */ + movb $0x08, %ah + int $0x13 /* get drive parameters; returns CH LSB of max cyl., CL(7-6) MSb max cyl., */ + /* CL(5-0) max sector, DH max head, DL drive qty, ES:DI floppy parameter table */ + movb %ch, %bl /* transfer maximum cylinder number */ + movb...

The handover protocol uses ED as partition type but the comment above it still mentions EE Signed-off-by: Ruben Kerkhof <ruben at rubenkerkhof.com> --- mbr/gptmbr.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mbr/gptmbr.S b/mbr/gptmbr.S index 7f450d3..8ab6b50 100644 --- a/mbr/gptmbr.S +++ b/mbr/gptmbr.S @@ -194,7 +194,7 @@ found_part: pushw %di /* 80 00 00 00

...ouldn't the sequence of pop word [cs:bsSecPerTrack] pop word [cs:bsHeads] be the reverse sequence of pushw %cx /* -16: Save sectors on the stack */ pushw %ax /* -18: Save heads on the stack */ ? Can it be that the two POPW which would need to swap places are the two byte groups "8f 06 28 30 2e" and "8f 06 2a 30 5a" near byte position 64 of isolinux.bin : fb c0 78 70 59 2e 8f 06 28 30 2e 8f 06 2a 30 5a given that isohdpfx.S has: HYBRID_MAGIC = 0x70...

...movw $0x55aa, %bx xorw %cx, %cx xorb %dh, %dh @@ -167,20 +167,22 @@ next: read_sector_cbios: movb $0x42, %ah ; jmp read_common */ movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ (read_sector_cbios) - jmp 1f + jmp 2f 1: + xor %cx, %cx /* Clear EBIOS flag. */ +2: popw %dx pushw %cx /* EBIOS flag */ /* Get (C)HS geometry */ movb $0x08, %ah int $0x13 - andw $0x3f, %cx /* Sector count */ popw %bx /* EBIOS flag */ - pushw %cx /* -16: Save sectors on the stack */ movzbw %dh, %ax /* dh = max head */ incw %ax /* From 0-based max to count */ - pushw...

...ere remains as suspect in read_sector_cbios only this division: divb (sectors) There is a suspicious discrepancy in the code: heads = (stack-16) sectors = (stack-18) ... /* here we computer CHS values or just do some dummy computation for EBIOS */ andw $0x3f, %cx /* Sector count */ popw %bx /* EBIOS flag */ pushw %cx /* -16: Save sectors on the stack */ movzbw %dh, %ax /* dh = max head */ incw %ax /* From 0-based max to count */ pushw %ax /* -18: Save heads on the stack */ mulw %cx /* Heads*sectors -> sectors per cylinder */ Does "-16: Save sectors on the stack&...

...+ + /* convert drive-number to two hex characters and insert them into the boot message */ + movw (drive_number), %dx + pushw %dx /* preserve for use by calculate_geometry */ + movw $msg_drive_number, %di + movb $0x02, %cl /* write two nibbles */ + call write_hex_value + +calculate_geometry: + popw %dx /* retrieve drive number */ + movb $0x08, %ah + int $0x13 /* get drive parameters; returns CH LSB of max cyl., CL(7-6) MSb max cyl., */ + /* CL(5-0) max sector, DH max head, DL drive qty, ES:DI floppy parameter table */ + movb %ch, %bl /* transfer maximum cylinder number */ + movb...

It is good to see this ----- Forwarded message from syslinux-bot for Martin Str|mberg <ams at ludd.ltu.se> ----- Date: Sat, 25 Mar 2017 05:54:09 -0700 From: syslinux-bot for Martin Str|mberg <ams at ludd.ltu.se> To: Syslinux commits mailing list <syslinux-commits at zytor.com> Cc: ams at ludd.ltu.se Subject: [syslinux:master] mbr/isohdpfx.S: correct pointer for heads/sectors

...ovb $0x42, %ah ; jmp read_common */ > movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ > (read_sector_cbios) > - jmp 1f > + jmp 2f > 1: > + xor %cx, %cx /* Clear EBIOS flag. */ > +2: > popw %dx > pushw %cx /* EBIOS flag */ > > /* Get (C)HS geometry */ > movb $0x08, %ah > int $0x13 > - andw $0x3f, %cx /* Sector count */ > popw %bx /* EBIOS flag */ > - pushw %cx...

...: + /* convert drive-number to two hex characters and insert them into the boot message */ + movw (drive_number), %dx + pushw %dx /* preserve for use by calculate_geometry */ + movw $msg_drive_number, %di + movb $0x02, %cl /* write two nibbles */ + call write_hex_value + +calculate_geometry: + popw %dx /* retrieve drive number */ + movb $0x08, %ah + int $0x13 /* get drive parameters; returns CH LSB of max cyl., CL(7-6) MSb max cyl., */ + /* CL(5-0) max sector, DH max head, DL drive qty, ES:DI floppy parameter table */ + movb %ch, %bl /* transfer maximum cylinder number */ + movb...

I wrote: > Also besides the 16/32 confusion in gptmbr.S there's more weirdness > that looks like a bug: > > /* Check to see if we have EBIOS */ ... > int $0x13 > popw %dx /* restore drive */ > movb $0x08, %ah /* get CHS geometry */ > jc 1f ... [More blather _why_ this is buggy.] Today I see that movb $0x08, %ah instruction. So just forget about this bug in gptmbr.S. Sorry. -- MartinS

...00, Thomas Schmitt via Syslinux wrote: > There is a suspicious discrepancy in the code: > > heads = (stack-16) > sectors = (stack-18) > > ... > /* here we computer CHS values or just do some dummy computation for EBIOS */ > andw $0x3f, %cx /* Sector count */ > popw %bx /* EBIOS flag */ > pushw %cx /* -16: Save sectors on the stack */ > movzbw %dh, %ax /* dh = max head */ > incw %ax /* From 0-based max to count */ > pushw %ax /* -18: Save heads on the stack */ > mulw %cx /* Heads*sectors -> sectors per cylinder */ > > Does &q...

...1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mbr/gptmbr.S b/mbr/gptmbr.S index 8ab6b50..7d98aee 100644 --- a/mbr/gptmbr.S +++ b/mbr/gptmbr.S @@ -213,7 +213,7 @@ found_part: movzwl %cx,%eax /* Length of GPT entry */ stosl - + rep; movsb /* GPT entry follows MBR entry */ popw %si -- 1.8.4.2

.../gptmbr.S >> +++ b/mbr/gptmbr.S >> @@ -213,7 +213,7 @@ found_part: >> >> movzwl %cx,%eax /* Length of GPT entry */ >> stosl >> - >> + >> rep; movsb /* GPT entry follows MBR entry */ >> popw %si >> > > The removal of that trailing tab character is valid change. > > What is needed to get the patch applied in the leading git repository? It has been applied to master. I believe there are a few other pending patches against master that need to be reviewed/applied as...

...6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mbr/isohdpfx.S b/mbr/isohdpfx.S index 17e1efe..f9e9691 100644 --- a/mbr/isohdpfx.S +++ b/mbr/isohdpfx.S @@ -175,12 +175,12 @@ next: /* Get (C)HS geometry */ movb $0x08, %ah int $0x13 - andw $0x3f, %cx /* Sector count */ popw %bx /* EBIOS flag */ - pushw %cx /* -16: Save sectors on the stack */ movzbw %dh, %ax /* dh = max head */ incw %ax /* From 0-based max to count */ - pushw %ax /* -18: Save heads on the stack */ + pushw %ax /* -16: Save heads on the stack */ + andw $0x3f, %cx /* Sector count */ + pushw %cx...