RE: [PATCH 2/3] x86: add a is_e820_ram() helper

From: Elliott, Robert (Server Storage)
Date: Thu Mar 26 2015 - 14:47:31 EST




> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Christoph Hellwig
> Sent: Thursday, March 26, 2015 11:43 AM
> To: Boaz Harrosh
> Cc: Christoph Hellwig; Ingo Molnar; linux-nvdimm@xxxxxxxxxxx; linux-
> fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx;
> ross.zwisler@xxxxxxxxxxxxxxx; axboe@xxxxxxxxx
> Subject: Re: [PATCH 2/3] x86: add a is_e820_ram() helper
>
> On Thu, Mar 26, 2015 at 05:49:38PM +0200, Boaz Harrosh wrote:
> > > + memmap=nn[KMG]!ss[KMG]
> > > + [KNL,X86] Mark specific memory as protected.
> > > + Region of memory to be used, from ss to ss+nn.
> > > + The memory region may be marked as e820 type 12 (0xc)
> > > + and is NVDIMM or ADR memory.
> > > +
> >
> > Do we need to escape "\!" this character on grub command line ? It might
> > help to note that. I did like the original "|" BTW
>
> No need to escape it on the kvm command line, which is where I tested
> this flag only so far. If there is a strong argument for "|" I'm happy
> to change it.

I agree with Boaz that ! is a nuisance if loading pmem as a module
with modprobe from bash.

The ! does work fine in the grub2 command line if the driver is
built-in. I added it to /etc/default/grub like this:
GRUB_CMDLINE_LINUX="<other parameters> memmap=8G!18G"
and grub-mkconfig placed it in /boot/efi/EFI/centos/grub.cfg
with no issues.

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