search for: read_common

..., %dh stc int $0x13 jc 1f cmpw $0xaa55, %bx jne 1f andw $1,%cx /* Bit 0 = fixed disk subset */ jz 1f /* We have EBIOS; patch in the following code at read_sector_cbios: movb $0x42, %ah ; jmp read_common */ movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ (read_sector_cbios) jmp 1f 1: This is my interpretation: David's machine's BIOS returns no carry indicating maybe support. However it doesn't set BX to the correct value, so is...

...jc 1f > cmpw $0xaa55, %bx > jne 1f > andw $1,%cx > /* Bit 0 = fixed disk subset */ > jz 1f > > /* We have EBIOS; patch in the following code at > read_sector_cbios: movb $0x42, %ah ; jmp read_common */ > movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ > (read_sector_cbios) > jmp 1f > 1: > > > This is my interpretation: > > David's machine's BIOS returns no carry indicating maybe > support. However it...

...uot;G\r\n" + pop %si +#endif jmp 1f /* We have non-GPT partition information */ 2: +#ifdef DEBUG_PRINT + push %si + call print_string + .ascii "M\r\n" + pop %si +#endif + movl 8(%si), %ecx #endif 1: @@ -167,14 +181,34 @@ next: read_sector_cbios: movb $0x42, %ah ; jmp read_common */ movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ (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...

Hi, i am looking now at the code which i assume loads the rest of isolinux.bin. The entry point for program execution from the MBR is obviously at http://git.zytor.com/syslinux/syslinux.git/tree/core/isolinux.asm#n186 (Do i get it right that this is the Intel syntax ? (Gronfff)) If POP yields the victim of the most recent not yet popped PUSH, then this does not look correctly coordinated

...heck to see if we have EBIOS */ pushw %dx /* drive number */ - movb $0x41, %ah /* %al == 0 already */ + movb $0x41, %ah 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...

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.

...xorw %cx, %cx xorb %dh, %dh stc int $0x13 popw %dx /* restore drive */ movb $0x08, %ah /* get CHS geometry */ jc 1f cmpw $0xaa55, %bx jne 1f shrw %cx /* Bit 0 = fixed disk subset */ jnc 1f /* We have EBIOS; patch in the following code at read_sector_cbios: movb $0x42, %ah ; jmp read_common */ movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ (read_sector_cbios) /* * read sector size. * Should not fail but if it does I assume that at least * previous 512 value is not overridden */ movb $0x48, %ah movw %sp, %si 1: /* Get (C)HS geometry */ int $0x13 A...

...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 512 value is not overridden + */ + movb $0x48, %ah + movw %sp, %si + jmp 2f /* this can be replaced by a .byte 0xbf to...

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

...number */ movb $0x41, %ah /* %al == 0 already */ movw $0x55aa, %bx xorw %cx, %cx xorb %dh, %dh stc int $0x13 jc 1f cmpw $0xaa55, %bx jne 1f andw $1,%cx /* Bit 0 = fixed disk subset */ jz 1f /* We have EBIOS; patch in the following code at read_sector_cbios: movb $0x42, %ah ; jmp read_common */ movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ (read_sector_cbios) #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: pop %si #else 1: #endif popw %dx pushw %cx /* EBIOS flag...

...that will receive the sector (should be 0x7C00) */ + pushw %bx /* buffer offset */ + pushw $1 /* sector count always 1 */ + pushw $16 /* size of disk address packet */ + movw %sp, %si /* address of disk address packet (on stack) */ + + testb $0x42, read_op /* using LBa addressing? */ + jz read_common /* Use LBA extended addressing */ + +read_sector_chs: + divl (sectors_cylinder) /* LBA in DX:AX inherited from above */ + shlb $6, %ah /* quotient is the cylinder number */ + movb %ah, %cl /* cylinder high bits (7-6) */ + movb %al, %ch /* cylinder low bits (7-0) */ + xchgw %dx, %ax /* remain...

...that will receive the sector (should be 0x7C00) */ + pushw %bx /* buffer offset */ + pushw $1 /* sector count always 1 */ + pushw $16 /* size of disk address packet */ + movw %sp, %si /* address of disk address packet (on stack) */ + + testb $0x42, read_op /* using LBa addressing? */ + jz read_common /* Use LBA extended addressing */ + +read_sector_chs: + divl (sectors_cylinder) /* LBA in DX:AX inherited from above */ + shlb $6, %ah /* quotient is the cylinder number */ + movb %ah, %cl /* cylinder high bits (7-6) */ + movb %al, %ch /* cylinder low bits (7-0) */ + xchgw %dx, %ax /* remain...

...that will receive the sector (should be 0x7C00) */ + pushw %bx /* buffer offset */ + pushw $1 /* sector count always 1 */ + pushw $16 /* size of disk address packet */ + movw %sp, %si /* address of disk address packet (on stack) */ + + testb $0x42, read_op /* using LBA addressing? */ + jz read_common /* Use LBA extended addressing */ + +read_sector_chs: + divl (sectors_cylinder) /* LBA in DX:AX inherited from above */ + shlb $6, %ah /* quotient is the cylinder number */ + movb %ah, %cl /* cylinder high bits (7-6) */ + movb %al, %ch /* cylinder low bits (7-0) */ + xchgw %dx, %ax /* remain...

This set of patches add some support for sector size >512. Currently it fixes extlinux, MBR for GPT and ext partitions. Other code is unaffected. This set of patches has been tested on a read Dell machine running a beta firmware.