Re: Boot from 4TB USB jhard drive

[Andrei Borzenkov]

20.03.2016 09:38, Emilio Lazo Zaia пишет:
> 
> On 20/03/16 00:35, Andrei Borzenkov wrote:
>> (...)
>> Create rescue image that can be used to boot off CD/USB
>>
>> pkgdatadir=$PWD ./grub-mkrescue -d grub-core -o /tmp/grub.iso
>>
>> This creates ISO image suitable for both CD and HDD boot. If using USB
>> stick, just dd this image on full stick. When booting from it, you will
>> end in GRUB command prompt.
> Dumped into a USB stick...
>> Check what
>>
>> ls -l
>> in GRUB CLI says. What sector size GRUB detects for your disk? Does GRUB
>> see partitions on your disk? Do they look reasonable (size, offset)? If
>> yes, try
> It says "Device hd2: No known filesystem detected - Sector size 4096B -
> Total size 3906984960KiB"
> 
> Partitions are not detected! In the previous test (GRUB 2.00-7) it
> doesn't show the sector size but the sector size it detects is 512B
> because of total sectors and partition offsets. In that test, ls -l says:
> 

No, GRUB internally works with 512B sectors and converts them when doing
disk IO as appropriate. So this does not say anything about device
sector size; display was added later.

> Device hd2: No known filesystem detected - Total size 7813969920
>     Partition hd2,gpt2: No known ... - Starts at 2048 ...
>     Partition hd2,gpt1: No known ... - Starts at 64 ...
> 
> Total size of 7813969920 sectors with 512 bytes per sector is also
> 3906984960KiB. Partition 1 starts at sector 64 (assuming 512B sectors)
> is the same as it starts at sector 8 (4096B sectors, as gpart shows).
> The same applies to partition 2, which starts at sector 2048 on 512B
> units, or 256 on 4096B units.
>>
>> insmod lvm
>> ls -l
>>
>> again. Does GRUB detect LVs?
> Nein. It doesn't detect LVs with the iso hybrid image I dumped into an
> USB stick, but it detect LVs and load kernel with GRUB 2.00-7 installed
> on laptop's hard drive.

So we additionally have regression against 2.00 :(

Please test attached patch; it is the only real change in biosdisk
driver comparing with 2.00.

>> Do you have serial port (RS-2323) on your system and another system that
>> can be used to connect to serial port? This would make capturing output
>> much easier.
> I'm sorry, I don't have serial ports.
> 
> Emilio.

biosdisk_200.patch
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