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SubjectRE: [PATCH v5 0/5] cramfs refresh for embedded usage
Date
On Friday, October 06, 2017, Christoph Hellwig wrote:
> This is still missing a proper API for accessing the file system,
> as said before specifying a physical address in the mount command
> line is a an absolute non-no.
>
> Either work with the mtd folks to get the mtd core down to an absolute
> minimum suitable for you, or figure out a way to specify fs nodes
> through DT or similar.

On my system, the QSPI Flash is memory mapped and set up by the boot
loader. In order to test the upstream kernel, I use a squashfs image and
mtd-rom.

So, 0x18000000 is the physical address of flash as it is seen by the
CPU.

Is there any benefit to doing something similar to this?

/* File System */
/* Requires CONFIG_MTD_ROM=y */
qspi@18000000 {
compatible = "mtd-rom";
probe-type = "map_rom";
reg = <0x18000000 0x4000000>; /* 64 MB*/
bank-width = <4>;
device-width = <1>;

#address-cells = <1>;
#size-cells = <1>;

partition@800000 {
label ="user";
reg = <0x0800000 0x800000>; /* 8MB @ 0x18800000 */
read-only;
};
};


Of course this basically ioremaps the entire space on probe, but I think
what you really want to do is just ioremap pages at a time (maybe..I
might not be following your code correctly)


Chris

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