Messages in this thread Patch in this message | | | Date | Wed, 01 Jul 2015 20:56:58 -0700 | From | Dan Mick <> | Subject | failing while writing to disk with BIOS in realmode setup |
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What might I be doing wrong? Why won't this code succeed to write to the (otherwise empty) drive 1 from kernel setup's main? I'm 100% certain this is the code I'm booting (with grub/bzImage); it's as though the intcalls just never happen (or fail for some reason I can't get telemetry on, which is why I'm trying this technique in the first place).
--- /var/tmp/main.c 2015-06-30 14:08:52.435618099 -0700 +++ arch/x86/boot/main.c 2015-07-01 20:33:32.227506260 -0700 @@ -132,6 +131,8 @@ } }
+char block[512] = "DJM WAS HERE "; + void main(void) { /* First, copy the boot header into the "zeropage" */ @@ -142,6 +143,22 @@ if (cmdline_find_option_bool("debug")) puts("early console in setup code\n");
+ struct biosregs ireg, oreg; + initregs(&ireg); + ireg.ah = 0; // reset drive 81 + ireg.dl = 0x81; + intcall(0x13, &ireg, &oreg); + + initregs(&ireg); + ireg.ah = 0x03; // write AL sectors to drive DL CHS CH/DH/CL + ireg.al = 1; + ireg.dl = 0x81; + ireg.cl = 1; + ireg.dh = 0; + ireg.es = ds(); + ireg.bx = (uint)(uintptr_t)█ + + intcall(0x13, &ireg, &oreg); /* End of heap check */ init_heap();
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