{"id":798,"date":"2020-12-06T18:07:54","date_gmt":"2020-12-06T18:07:54","guid":{"rendered":"https:\/\/www.ecsdump.net\/?page_id=798"},"modified":"2020-12-09T06:35:25","modified_gmt":"2020-12-09T11:35:25","slug":"jfs-boot-block-bochs-adventure","status":"publish","type":"page","link":"https:\/\/www.ecsdump.net\/?page_id=798","title":{"rendered":"JFS Boot Block :: Bochs Adventure"},"content":{"rendered":"
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So, getting a MBR and os2boot on a hard drive image was a real pain. None of the current CDs would boot to a point where I could get the job done. I resorted to doing it the hard way. I mounted an old 630 meg IDE hard drive (just having this around should label me a packrat) and booted the system with an eCS 2.0 RC4 CDROM. Using the eCS tools I made a compatible partition which was bootable and wrote the MBR. Next, I did a long JFS format on the partition which completed but with errors toward the end of the format process.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Geshi:<\/div>\n
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eax: 0x0000aa55 43605\necx: 0x00000000 0\nedx: 0x00000080 128\nebx: 0x00000000 0\nesp: 0x0000ffdc 65500\nebp: 0x00000000 0\nesi: 0xffff0000 -65536\nedi: 0x0008fdba 589242\neip: 0x00007c00\neflags 0x00000082\nIOPL=0 id vip vif ac vm rf nt of df if tf SF zf af pf cf\n\u00a0\ncs:s=0x0000, dl=0x0000ffff, dh=0x00009b00, valid=1\nds:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1\nss:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=7\nes:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1\nfs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1\ngs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1\nldtr:s=0x0000, dl=0x00000000, dh=0x00000000, valid=0\ntr:s=0x0000, dl=0x00000000, dh=0x00000000, valid=0\ngdtr:base=0x000faeb2, limit=0x30\nidtr:base=0x00000000, limit=0x3ff<\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
Phase 1 \u2014 The MBR<\/p>\n
In brief, control is passed from BIOS to the loaded MBR code at 07C0:0000. The code relocates itself to 07E0:0000, checks for a Boot Manager partition, and checks for a bootable partition. Once a bootable partition is found, the partition boot record or more correctly the BIOS parameter block (BPB<\/a>) is loaded at 07C0:0000 and control is passed to it at 07C0:0000.<\/p>\n
Remember, as I understand the MBR is created by the LVM utility (ex: LVM \/NEWMBR). At this point the system is using INT13 calls to interface with the drive. The errors that can be encountered during this phase are:<\/p>\n