search for: ebpb

...systems, only the first sector is used. For FAT32, there are 32 sectors that are reserved by the FS, and I've come up with the following handy chart for which sectors are used where: Sector layout for FAT32 **partition** boot record. ------------------------ sector purpose 0 - boot sector / EBPB offset 510 = 0xFF, 511 = 0xAA 1 - FSINFO Sector offset 510 = 0xFF, 511 = 0xAA 2 - boot 3 offset 510 = 0xFF, 511 = 0xAA 3 - unused 4 - unused 5 - unused 6 - backup boot sector / EBPB offset 510 = 0xFF, 511 = 0xAA 7 - backup FSINFO Sector offset 510 =...

...uot; 192 entries = 192 potential sectors for ldlinux.sys? > > 5. Installer puts the first 512 bytes of ldlinux.bin into the boot sector > > ... by reading the existing VBR, modifying ONLY the bytes allowed for > code, then writing the modified VBR back. > So as not to ruin the EBPB or signature, e.g.? > > 6. Installer modifies code in VBR (a specific byte?) to indicate which > block > > contains first 512 bytes of ldlinux.sys > > It's 8 bytes for a 64-bit address located at the labels "Sect1Ptr0" > and "Sect1Ptr1". These are...

...rs for ldlinux.sys? Correct. >> > 5. Installer puts the first 512 bytes of ldlinux.bin into the boot >> > sector >> >> ... by reading the existing VBR, modifying ONLY the bytes allowed for >> code, then writing the modified VBR back. > So as not to ruin the EBPB or signature, e.g.? EBPB. Without it, a FAT file system is near impossible to reliably read. >> > 6. Installer modifies code in VBR (a specific byte?) to indicate which >> > block >> > contains first 512 bytes of ldlinux.sys >> >> It's 8 bytes for a 64-...

...inux.sys, which appears to be around 68K, but you can get a lot more in 15K than 512 bytes. So: 1. How much of ldlinux.sys gets loaded into the reserved sectors? Or is it nothing, and just use the VBR? 2. When loading the VBR, it skips over the bytes reserved for boot instruction, name, and FAT32 EBPB? Ah, right, I see it in the ldlinux.bin. First 11 bytes are jump instruction and SYSLINUX label, then all nulls where the EBPB would be. Nice. -- Avi Deitcher avi at deitcher.net Follow me http://twitter.com/avideitcher Read me http://blog.atomicinc.com

...uot;guts". ("syslinuxoscopy"? Bad humour day...) > When the partition in question was formatted as FAT32, SYSLINUX's installer puts (bootable) > code within the VBR That being the few hundred bytes of difference between ldlinux.bin and ldlinux.sys (minus the nulls for the ebpb, and the all-nulls second 512-bytes, etc), and whose source is diskboot.inc (thanks again Gene). > and puts one or two files (including at least > "ldlinux.sys", a file) onto the filesystem's data area. Yup. > the SYSLINUX'S installer for FAT32 first puts "ldlinux...

Gene, thanks for doing "Reply-All". I only get digest, so this keeps me in the loop. Appreciated. > which appears to be included in diskstart.inc. I will have to dig in and > see > > how this all gets compiled (pointers always appreciated :-) ). > > Yes. > Is the build process documented? Or am I just going to have to plod through the makefiles? > As Ady said,