Using mtdblock as root device

PATCH Robert Kaiser 2 participants 3 messages Mar 6, 2001 – Mar 7, 2001 1 message not in the archive Memory technology devices (MTD)

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Robert Kaiser

author

2001-03-06 12:11 UTC #0 lore raw

Hi,

I just tried to build a system that uses jffs on /dev/mtdblock0 as root fs. This didn't work right away because the kernel did not honor the option "root=/dev/mtdblock0" . This is because mtdblock devices are not listed in the list of known root devices in the kernel (see "root_dev_names" in file init/main.c). After applying the attached patch, using mtdblock as rootfs worked nicely.

Now my question is: is there any particular reason (other than "nobody has told Linus") why this is not already in the standard kernel ?

If there isn't, should I go ahead and submit my patch to Linus ?

Cheers

Rob

----------------------------------------------------------------
Robert Kaiser email: [email protected]
SYSGO RTS GmbH
Am Pfaffenstein 14 phone: (49) 6136 9948-762
D-55270 Klein-Winternheim / Germany fax: (49) 6136 9948-10

init/main.c renamed from init/main.c.orig +18 -0

@@ -273,6 +273,24 @@
 #ifdef CONFIG_NFTL
 	{ "nftla", 0x5d00 },
 #endif
+#ifdef CONFIG_MTD
+	{ "mtdblock0", 0x1f00 },
+	{ "mtdblock1", 0x1f01 },
+	{ "mtdblock2", 0x1f02 },
+	{ "mtdblock3", 0x1f03 },
+	{ "mtdblock4", 0x1f04 },
+	{ "mtdblock5", 0x1f05 },
+	{ "mtdblock6", 0x1f06 },
+	{ "mtdblock7", 0x1f07 },
+	{ "mtdblock8", 0x1f08 },
+	{ "mtdblock9", 0x1f09 },
+	{ "mtdblock10", 0x1f0a },
+	{ "mtdblock11", 0x1f0b },
+	{ "mtdblock12", 0x1f0c },
+	{ "mtdblock13", 0x1f0d },
+	{ "mtdblock14", 0x1f0e },
+	{ "mtdblock15", 0x1f0f },
+#endif
 	{ NULL, 0 }
 };

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Robert Kaiser

author

2001-03-06 13:49 UTC #2 lore raw

Hi,

Quoted 6 lines · On Die, 06 M�r 2001 you wrote:

It's been submitted many many times. If you do submit it again, please add nftl[bcd] and ftl[abcd] too, and I don't think you actually need anything more than
	{"mtdblock", 0x1f00},
for the mtdblock devices, because they're handled just like partitions.

Hmm, I for one have two mtd devices on my platform, both of which I'd like to be able to use as root device. But I agree that 16 is probably a bit overkill. How about:

	{"mtdblock0", 0x1f00},
	{"mtdblock1", 0x1f01},
or:
	{"mtdblock", 0x1f00},
	{"mtdblock0", 0x1f00},
	{"mtdblock1", 0x1f01},

Rob

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David Schleef

2001-03-07 02:07 UTC #3 lore raw

Quoted 14 lines · Robert Kaiser

Hi,
Quoted 6 lines · On Die, 06 Mär 2001 you wrote:
It's been submitted many many times. If you do submit it again, please add nftl[bcd] and ftl[abcd] too, and I don't think you actually need anything more than
	{"mtdblock", 0x1f00},
for the mtdblock devices, because they're handled just like partitions.
Hmm, I for one have two mtd devices on my platform, both of which I'd like to be able to use as root device. But I agree that 16 is probably a bit overkill. How about:

Quoted 6 lines

	{"mtdblock0", 0x1f00},
	{"mtdblock1", 0x1f01},
or:
	{"mtdblock", 0x1f00},
	{"mtdblock0", 0x1f00},
	{"mtdblock1", 0x1f01},

Just {"mtdblock", 0x1f00} will suffice, because any number appended will be converted to an integer and be added to the base number given.

Check the implementation of name_to_kdev_t in init/main.c for details.

dave...

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