search for: movzbw

...tors) 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" contradict "sectors = (stack-18)" ? Have a nice day :) Thoma...

...x/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 with the MBR. isohdpfx.S has: 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 */ pushw %bx /* -20: EBIOS flag */ isolinux.asm has: ; The following values will have been pushed onto the ; entry...

...de: > > 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" contradict "sectors = (stack-18)" ? Y...

...+ 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 %ax /* -18: Save heads on the stack */ + pushw %ax /* -16: Save heads on the stack */ + andw $0x3f, %cx /* Sector count */ + pushw %cx /* -18: Save sectors on the stack */ mulw %cx /* Head...

...hdpfx.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 /* -18: Save sectors on the stack */ mulw %cx /* Heads*sectors -> sectors...

...d_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 %ax /* -18: Save heads on the stack */ + pushw %ax /* -16: Save heads on the stack */ + andw $0x3f, %cx /* Sector count */ + pushw %cx /* -18: Save sectors on the stack */ mulw %cx /* Heads*sectors -> sectors...

...nt $0x13 + + /* here we computer CHS values of just do some dummy computation for EBIOS */ andw $0x3f, %cx /* Sector count */ - movw %sp, %bp /* %bp -> frame pointer: LEAVE UNCHANGED */ - pushw %cx /* -2(%bp) Save sectors on the stack */ + pushw %cx /* -32(%bp) Save sectors on the stack */ movzbw %dh, %ax /* dh = max head */ incw %ax /* From 0-based max to count */ mulw %cx /* Heads*sectors -> sectors per cylinder */ /* Save sectors/cylinder on the stack */ - pushw %dx /* -4(%bp) High word */ - pushw %ax /* -6(%bp) Low word */ + pushw %dx /* -34(%bp) High word */ + pushw %ax...

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

...> > /* 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 co...

Hi, funny or enlightening observation: With my qemu-system-i386 it would work if the detected Heads/Cylinder and Sectors/Head factors would change positions ! The effective read operation seems to use H/C = 32 , S/H = 63. The correct LBA would be addressed by H/C = 63 , S/H = 32. -------------------------------------------------------------------------- Reasoning: I have transplanted the

Hi, C/H/S addressing and reading of first block seems to be ok in isohdpfd.bin. The main suspect for the failure of the attempt with isohdpfd.bin is the number or content of the blocks read after the first one. But i have no clue why isohdpfc.bin should do better than isohdpfd.bin. They differ just by one instruction (JC = 0x72 versus JMP = 0xEB) which both are performed before the reading and

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.

...max head, DL drive qty, ES:DI floppy parameter table */ + movb %ch, %bl /* transfer maximum cylinder number */ + movb %cl, %bh + shrb $6, %bh /* move bits into correct positions */ + pushw %bx /* preserve maximum cylinder number */ + incb %dh /* convert zero-based maximum to quantity */ + movzbw %dh, %ax /* DH = maximum head number */ + pushw %ax /* preserve maximum head number */ + andw $0x3f, %cx /* mask to enforce maximum sector number 63 */ + pushw %cx /* preserve sector count */ + incw %ax /* convert zero-based maximum head number to quantity */ + mulw %cx /* sectors per...

...: #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 */ 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 */ pushw %bx /* -20: EBIOS flag */ /* Save sectors/cylinder on the stack */ pushw %dx /* -22: High word */ pushw %ax...

...max head, DL drive qty, ES:DI floppy parameter table */ + movb %ch, %bl /* transfer maximum cylinder number */ + movb %cl, %bh + shrb $6, %bh /* move bits into correct positions */ + pushw %bx /* preserve maximum cylinder number */ + incb %dh /* convert zero-based maximum to quantity */ + movzbw %dh, %ax /* DH = maximum head number */ + pushw %ax /* preserve maximum head number */ + andw $0x3f, %cx /* mask to enforce maximum sector number 63 */ + pushw %cx /* preserve sector count */ + incw %ax /* convert zero-based maximum to quantity */ + mulw %cx /* sectors per cylinder =...

...max head, DL drive qty, ES:DI floppy parameter table */ + movb %ch, %bl /* transfer maximum cylinder number */ + movb %cl, %bh + shrb $6, %bh /* move bits into correct positions */ + pushw %bx /* preserve maximum cylinder number */ + incb %dh /* convert zero-based maximum to quantity */ + movzbw %dh, %ax /* DH = maximum head number */ + pushw %ax /* preserve maximum head number */ + andw $0x3f, %cx /* mask to enforce maximum sector number 63 */ + pushw %cx /* preserve sector count */ + incw %ax /* convert zero-based maximum head number to quantity */ + mulw %cx /* sectors per...

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.