On 01/08/2016 02:03 AM, Pascal Hambourg wrote: > Christian Seiler a écrit : >> Problem is that GPT doesn't have such a gap. > > GPT usually also has such a gap for partition alignment purpose. Well sure, but MBR also has all the CHS baggage - and while it isn't used anymore on modern systems, there still is the de-factor standard of aligning the first partition with the first CHS-sector that is so ingrained historically that the gap between MBR and the first partition is something that may be relied on. Whereas with GPT, which only uses LBA from the get-go, you could in principle create a partition at the first block after the end of the partition table, so on 512-byte/"LBA-sector" disks with the minimum partition table size, that'd be LBA #34 - with no gap at all. Or to put it differently: because of the CHS baggage of MBR, there is software that wouldn't support it if the first partition wasn't aligned; for compatibility reasons every tool that manipulates MBR partitions will therefore want to leave a gap after the MBR. And while many GPT tools will also leave a gap for alignment purposes, this isn't required anymore, and any conforming GPT implementation will cope with non-"aligned" GPT partitions. So yes, my statement was an oversimplification - but it is not unreasonable to have a gapless disk with GPT - hence the explanation why grub doesn't use this gap anymore. (Because you could also create a partition there afterwards.) >> At least Jessie's d-i appears to only be able to create MBR >> partition tables > > That's wrong. I have created GPT partition tables with Wheezy's > installer. IIRC, it creates a GPT partition table by default when booted > in EFI mode. I didn't try EFI mode recently. But in legacy BIOS mode, I've found no option of making the installer create a GPT table - I actually had to use a shell to do it manually. (If there is an option, it's *too* well hidden.) Regards, Christian
Attachment:
signature.asc
Description: OpenPGP digital signature