ATA 4 KiB sector issues.
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From: Daniel Taylor on 9 Mar 2010 19:30 >> GPT can not be used for boot disks in non-EFI systems, right? > IIUC, I think any BIOS should be able to do so as it only cares about the code part of MBR > not the partitions and even with GPT the MBR remains the same with the partition part > describing the rest of the while disk as a single chunk containing GPT managed area. The > only problem is the older operating systems (like XP) which don't understand GPT wouldn't be > able to access those partitions. > Thanks. The MBR in a GPT installation doesn't map the first GPT partition, it maps the entire drive drive after the first sector, as well as marking it type 0xEE. The start LBA of the file system is not correctly located in the MBR. I will run some experiments to see if any of the systems on my desk can boot Linux from a GPT. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: H. Peter Anvin on 9 Mar 2010 19:40 On 03/09/2010 02:46 PM, Greg Freemyer wrote: > <snip> >> >> As far as partitioning... I believe we should be using GPT partition tables >> where possible. Even on non-EFI systems, it's simply a much better >> partition table format. >> >> -hpa > > GPT can not be used for boot disks in non-EFI systems, right? > It can. The BIOS doesn't care about the partition table at all -- all it does is load the MBR. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 9 Mar 2010 19:40 Hello, On 03/09/2010 03:50 AM, H. Peter Anvin wrote: > Well, apparently Western Digital are looking at it for USB drives due to > XP compatibility requirements -- those presumably are ATA internally and > use a USB-ATA bridge. This should work right now as long as the bridge chip doesn't screw up, which we can't do much about anyway. USB is used as SCSI transport and SCSI layer has been working fine with devices with differing sector sizes for quite some time. > On the flipside, though, there really is very little net benefit to 4K > as opposed to 512 byte logical sectors: the additional protocol overhead > is relatively minimal, and as long as writes are aligned full blocks, > there shouldn't be any additional overhead on either the OS or the drive > side. On the plus side, you get full compatibility with the existing > software stack. The equation really seems rather simple. Yeap, for addressing, whether 9 bit is shifted or 12 doesn't really matter. That's only 8 times difference which may be breached in probably under three years. If the current 48 bit addressing limit is reached, we would be far better off introducing 64 or 128 bit addressing. That was the reason why I thought that I would never see an ATA disk w/ 4KiB logical sector and got pretty surprised that it was being considered for XP compatibility where 3 year offset could be pretty meaningful. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: H. Peter Anvin on 9 Mar 2010 19:40 On 03/09/2010 04:26 PM, Tejun Heo wrote: > >> I will run some experiments to see if any of the systems on my desk can boot >> Linux from a GPT. > > I'm not sure about grub although I strongly suspect recent version of > it should work but AFAICS lilo should definitely work as it doesn't > care how the disk is logically organized at all. > In the case of Syslinux, you have to install gptmbr.bin, but otherwise it works unmodified (Syslinux itself doesn't care about the partition table at all.) Note: the official standard for GPT booting on BIOS is still evolving, so I might change gptmbr to match the new standard. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Martin K. Petersen on 10 Mar 2010 00:10
>>>>> "Karel" == Karel Zak <kzak(a)redhat.com> writes: [Cleaned up the CC: list from hell] Karel> # cat /sys/block/md8/queue/{minimum,optimal}_io_size Karel> 65536 65536 This one had me puzzled. We set min_io and opt_io correctly in raid5.c depending on number of non-parity disks. And yet it turns into something nonsensical after. Turns out we overrun unsigned int calculating the lowest common multiple in the stacking function. That's why we ended up with the wrong value. I never noticed this because my userland topology regression test tool uses unsigned long. I'll get a patch off to Jens right away. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |