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mtd: phram: dot not crash when built-in and passing boot param 

This patch is based on Ville Herva's similar patch to block2mtd.

Trying to pass a parameter through the kernel command line when built-in would
crash the kernel, as phram_setup() was called so early that kmalloc() was not
functional yet.

This patch only saves the parameter string at the early boot stage, and parses
it later when init_phram() is called. The same happens in both module and
built-in cases.

With this patch, I can boot with a statically-compiled phram, and mount a
ext2 root fs from physical RAM, without the need for a initrd.

This has been tested in built-in and module cases, with and without a
parameter string.

Artem: amended comments a bit

Signed-off-by: Hervé Fache <h-fache@ti.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Hervé Fache 2012-03-13 16:07:53 +01:00 committed by David Woodhouse
parent 09ef90d965
commit b2a2a84d35
1 changed files with 30 additions and 3 deletions
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33
drivers/mtd/devices/phram.c
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@ -39,7 +39,8 @@ static int phram_erase(struct mtd_info *mtd, struct erase_info *instr)
memset(start + instr->addr, 0xff, instr->len);
/* This'll catch a few races. Free the thing before returning :)
/*
* This'll catch a few races. Free the thing before returning :)
* I don't feel at all ashamed. This kind of thing is possible anyway
* with flash, but unlikely.
*/
@ -204,7 +205,17 @@ static inline void kill_final_newline(char *str)
return 1; \
} while (0)
static int phram_setup(const char *val, struct kernel_param *kp)
/*
* This shall contain the module parameter if any. It is of the form:
* - phram=<device>,<address>,<size> for module case
* - phram.phram=<device>,<address>,<size> for built-in case
* We leave 64 bytes for the device name, 12 for the address and 12 for the
* size.
* Example: phram.phram=rootfs,0xa0000000,512Mi
*/
static __initdata char phram_paramline[64+12+12];
static int phram_setup(const char *val)
{
char buf[64+12+12], *str = buf;
char *token[3];
@ -253,12 +264,28 @@ static int phram_setup(const char *val, struct kernel_param *kp)
return ret;
}
module_param_call(phram, phram_setup, NULL, NULL, 000);
static int __init phram_param_call(const char *val, struct kernel_param *kp)
{
/*
* This function is always called before 'init_phram()', whether
* built-in or module.
*/
if (strlen(val) >= sizeof(phram_paramline))
return -ENOSPC;
strcpy(phram_paramline, val);
return 0;
}
module_param_call(phram, phram_param_call, NULL, NULL, 000);
MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
static int __init init_phram(void)
{
if (phram_paramline[0])
return phram_setup(phram_paramline);
return 0;
}