search for: xorw

...te if wanted EBIOS calls are supported or not as the and will mask away all but the interesting bit. The code: /* Check to see if we have EBIOS */ pushw %dx /* drive 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_secto...

...ot as the and will mask away all but the interesting > bit. > > > The code: > /* Check to see if we have EBIOS */ > pushw %dx /* drive 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...

...ebios_flag = (stack-20) secpercyl = (stack-24) BIOS_kbdflags = 0x417 BIOS_page = 0x462 /* gas/ld has issues with doing this as absolute addresses... */ .section ".bootsec", "a", @nobits .globl bootsec bootsec: .space 512 .text .globl _start _start: .byte 0x33, 0xed /* xorw %bp, %bp */ cli movw %bp, %ss movw $stack, %sp sti cld /* Check to see if we have a partition table entry */ xorl %ebx, %ebx xorl %ecx, %ecx #ifdef PARTITION_SUPPORT andw %si, %si /* %si == 0 -> no partition data */ jz 1f testb $0x7f, (%si) /* Invalid active flag field? */ jnz 1f...

...lign 4,,15 .globl _f .def _f; .scl 2; .type 32; .endef _f: pushl %ebp movddup _DA, %xmm2 movl %esp, %ebp xorl %eax, %eax .p2align 4,,10 L2: movapd _Y(%eax), %xmm0 movapd _X(%eax), %xmm1 mulpd %xmm2, %xmm1 subpd %xmm1, %xmm0 movapd %xmm0, _Y(%eax) addl $16, %eax cmpl $800, %eax jne L2 xorw %ax, %ax leave ret .globl _DA .data .align 16 _DA: .long 858993459 .long 1070805811 .comm _X, 800, 5 .comm _Y, 800, 5 It seems gcc emit more effectivenss instuction. Are there any clang command arguments to get the similar result? -------------- next part -------------- An HTML attachment...

...0000 0000 0000 0x11ef:0x5974: 0000 0000 0000 0000 0000 0000 0000 0000 0x11ef:0x5984: 0000 0000 0000 0000 0000 0000 0000 0000 023d: sel=11ef base=7fde0f20 limit=0000619f 16-bit rw- 0238: sel=11c7 base=7fdc1690 limit=0000010f 16-bit rw- Backtrace: =>1 0x11df:0x001a (0x11df:0x001a) 0x11df:0x001a: xorw %bp,%bp Modules: Module Address Debug info Name (69 modules) ELF 0x7be82000-7bf00000 Deferred ntdll<elf> \-PE 0x7be90000-7bf00000 \ ntdll ELF 0x7bf00000-7bf03000 Deferred <wine-loader> ELF 0x7eef7000-7ef2b...

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

...hdpfx.S index 17e1efe..14eca14 100644 --- a/mbr/isohdpfx.S +++ b/mbr/isohdpfx.S @@ -151,7 +151,7 @@ next: /* Check 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...

...x.S +++ b/mbr/isohdpfx.S @@ -65,6 +65,38 @@ bootsec: .text .globl _start _start: + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop .byte 0x33, 0xed /* xorw %bp, %bp */ cli movw %bp, %ss diff --git a/utils/Makefile b/utils/Makefile index acda8c0..44cb54f 100644 --- a/utils/Makefile +++ b/utils/Makefile @@ -51,7 +51,7 @@ isohdpfx.c: $(ISOHDPFX) isohdpfxarray.pl $(PERL) isohdpfxarray.pl $(ISOHDPFX) > $@ isohybrid: isohybrid.o isohdpfx.o - $(C...

...quot;movb $0x41, %ah" should be "movw $0x4100, %ax". 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 */ pushw %dx /* drive number */ movb $0x41, %ah /* %al == 0 already */ movw $0x55aa, %bx 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_c...

...0000 0000 0000 0x11e7:0x571c: 0000 0000 0000 0000 0000 0000 0000 0000 0x11e7:0x572c: 0000 0000 0000 0000 0000 0000 0000 0000 023c: sel=11e7 base=7fe1aae8 limit=0000863f 16-bit rw- 0238: sel=11c7 base=7fe00200 limit=0000010f 16-bit rw- Backtrace: =>1 0x11df:0x761a (0x11e7:0x0000) 0x11df:0x761a: xorw %bp,%bp Modules: Module Address Debug info Name (58 modules) ELF 0x7be83000-7bf00000 Deferred ntdll<elf> \-PE 0x7bea0000-7bf00000 \ ntdll ELF 0x7bf00000-7bf03000 Deferred <wine-loader> ELF 0x7ea22000-7ea36...

...0000 0000 0000 0x11e7:0x348e: 0000 0000 0000 0000 0000 0000 0000 0000 0x11e7:0x349e: 0000 0000 0000 0000 0000 0000 0000 0000 023c: sel=11e7 base=7bca5d48 limit=000054bf 16-bit rw- 0238: sel=11c7 base=7bc91900 limit=0000010f 16-bit rw- Backtrace: =>1 0x11df:0x001a (0x11e7:0x0000) 0x11df:0x001a: xorw %bp,%bp Modules: Module Address Debug info Name (52 modules) ELF 0x7b808000-7b845000 Deferred advapi32<elf> \-PE 0x7b820000-7b845000 \ advapi32 ELF 0x7b845000-7b8c9000 Deferred gdi32<elf> \-PE 0x7b860000-7b8...

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

...t to say I've managed to simulate David's error in qemu by forcing isohdpfx.bin to fail the EBIOS test. /* Check to see if we have EBIOS */ pushw %dx /* drive number */ movb $0x41, %ah /* %al == 0 already */ movw $0x55aa, %bx xorw %cx, %cx xorb %dh, %dh stc int $0x13 //XXX jc 1f jnc 1f cmpw $0xaa55, %bx jne 1f andw $1,%cx /* Bit 0 = fixed disk subset */ jz 1f With that jc changed to jnc you will invert the result o...

...ack-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 register values from entry point */ e_es = (e0_bot-4) e_si = (e0_bot-6) e_ds = (e0_bot-8) BIOS_page = 0x462 .globl _start _start: cli xorw %ax, %ax movw %ax, %ss movw $stack, %sp pushaw pushw %di /* es:di -> $PnP header */ pushw %es pushw %si pushw %ds sti cld pushw %cs popw %ds #ifdef DEBUG_START pushw %dx call crlf movw $(_start),%dx /* 0x0600 mbr.ld .text address */ call wrhexw call crlf call caddr caddr: pop...

...ally visible. doc: 7.56 */ +bootsec: + .space 512 /* set 512 bytes to zero. doc: 7.102 */ + + .text + .global _start +_start: + + /* All code from here until the relocation operation does nothing that relies */ + /* on the value of the instruction pointer */ + cli /* disable interrupts */ + xorw %ax, %ax /* reset to 0 */ + movw %ax, %ds /* reset data segment base */ + movw %ax, %ss /* reset stack segment base */ + movw $stack, %sp /* set stack pointer */ + movw %sp, %si /* address where BIOS loaded MBR, used as source address for relocation */ + pushw %es /* save Plug'n'Pla...

...ally visible. doc: 7.56 */ +bootsec: + .space 512 /* set 512 bytes to zero. doc: 7.102 */ + + .text + .global _start +_start: + + /* All code from here until the relocation operation does nothing that relies */ + /* on the value of the instruction pointer */ + cli /* disable interrupts */ + xorw %ax, %ax /* reset to 0 */ + movw %ax, %ds /* reset data segment base */ + movw %ax, %ss /* reset stack segment base */ + movw $stack, %sp /* set stack pointer */ + movw %sp, %si /* address where BIOS loaded MBR, used as source address for relocation */ + pushw %es /* save Plug'n'Pla...

...ally visible. doc: 7.56 */ +bootsec: + .space 512 /* set 512 bytes to zero. doc: 7.102 */ + + .text + .global _start +_start: + + /* All code from here until the relocation operation does nothing that relies */ + /* on the value of the instruction pointer */ + cli /* disable interrupts */ + xorw %ax, %ax /* reset to 0 */ + movw %ax, %ds /* reset data segment base */ + movw %ax, %ss /* reset stack segment base */ + movw $stack, %sp /* set stack pointer */ + movw %sp, %si /* address where BIOS loaded MBR, used as source address for relocation */ + movw %sp, %bp /* needed later if drive...

I am working on a Linux-based boot disk for my project (http://unattended.sourceforge.net/), and I have hit a snag. Under Linux 2.6, the kernel (via HDIO_GETGEO) always reports the C/H/S geometry of an IDE drive as X/16/63. But most BIOSes want to use the geometry Y/255/63. Most partitioning tools (including Parted) will take clues from an existing partition table and adapt to the BIOS values.

...iret + +deliver_to_host: + SWITCH_TO_HOST + /* Decode IDT and jump to hosts' irq handler. When that does iret, it + * will return to run_guest_once. This is a feature. */ + movl (LGUEST_PAGES_host_idt_desc+2)(%eax), %edx + leal (%edx,%ebx,8), %eax + movzwl (%eax),%edx + movl 4(%eax), %eax + xorw %ax, %ax + orl %eax, %edx + jmp *%edx + +/* Real hardware interrupts are delivered straight to the host. Others + cause us to return to run_guest_once so it can decide what to do. Note + that some of these are overridden by the guest to deliver directly, and + never enter here (see load_gue...

...iret + +deliver_to_host: + SWITCH_TO_HOST + /* Decode IDT and jump to hosts' irq handler. When that does iret, it + * will return to run_guest_once. This is a feature. */ + movl (LGUEST_PAGES_host_idt_desc+2)(%eax), %edx + leal (%edx,%ebx,8), %eax + movzwl (%eax),%edx + movl 4(%eax), %eax + xorw %ax, %ax + orl %eax, %edx + jmp *%edx + +/* Real hardware interrupts are delivered straight to the host. Others + cause us to return to run_guest_once so it can decide what to do. Note + that some of these are overridden by the guest to deliver directly, and + never enter here (see load_gue...