Re: [RFC v2] memmap: introduce cmdline parameter "memmap=nn[KMG]$" without start addr

[Dave Hansen]

On 6/28/22 05:45, lizhe.67@xxxxxxxxxxxxx wrote:
> From: Li Zhe <lizhe.67@xxxxxxxxxxxxx>
> 
> In current kernel we can use memmap=nn[KMG]$ss[KMG] to reserve an
> area of memory for userspace usage through /dev/mem. We have to
> determine the start addr and length. In our scenario, we need
> reserve or alloc large continuous physical memory at least 256M in
> 512G's machine, and need reserve more memory in larger machine, at
> just boot phase for a userspace program. And these memories will not
> be freed to system before system reboot. The userspace program can
> use the memory through /dev/mem to store some data. Besides, a
> hardware will need the data stored by the userspace program to do
> it's job. Why we need continuous memory is that the hardware can
> only access memory without mmu.

That's still a rather anemic description.

I don't think we want this code in the kernel with that description, sorry.

If you'd like to come back with an actual description, naming the exact
hardware that you have *AND* explaining sane reasons for why the
hardware doesn't have a normal kernel driver (or interface) like every
other piece of hardware, then we can talk.  But, otherwise, this isn't
something that can go upstream.