lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Sun, 09 Nov 2014 19:52:20 +0200
From:	Boaz Harrosh <>
To:	"Martin K. Petersen" <>
CC:	Jens Axboe <>, Matthew Wilcox <>,
	Dmitry Monakhov <>,
	linux-kernel <>,
	linux-fsdevel <>,
	Karel Zak <>
Subject: Re: [PATCH 4/5] brd: Request from fdisk 4k alignment

On 11/06/2014 07:25 PM, Martin K. Petersen wrote:
>>>>>> "Boaz" == Boaz Harrosh <> writes:
> Boaz,
> Boaz> Note that blk_queue_physical_block_size() also trashes io_min, but
> Boaz> we can leave this one to be 512. io_min as opposed to
> Boaz> physical_block_size will actually change Kernel behavior
>>> Care to elaborate?
> I wanted you to elaborate on how io_min changes kernel behavior.

OK You are correct. io_min changes behavior of Kernel in exactly the same
way as physical_block_size.

Through the call to queue_limit_alignment_offset() inside add_partition()
by setting hd_struct->alignment_offset

I do not know why I thought that only io_min does that, I can see now that
both effect the Kernel the same way. Which scares me a bit.

Will I have problems?

> It really sounds like either your fdisk is way too old or you are
> running it in DOS compat mode.
> I don't have a fundamental issue reporting pbs of 4K. But if you are
> only doing it to force a certain partition alignment then it sounds like
> a kernel fix for a userland problem.
> I've CC:ed Karel who can comment on fdisk partition alignment issues.

Thanks Martin. I agree, we should not fix user-mode problems. Please see
the other email with the exact numbers I get from fdisk. It looks like
when everything is 512 like default it would not align my partitions, but
with the 4k-phisical thing it would. What is the expected behavior we want?


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists