Re: [PATCH v3] Virtual memory size detection for 64 bit MIPS CPUs

[David Daney <ddaney@caviumnetworks.com>]

Guenter Roeck wrote:
> Linux kernel 2.6.32 and later allocates memory from the top of virtual memory
> space.
> 
> This patch implements virtual memory size detection for 64 bit MIPS CPUs
> to avoid resulting crashes.
> 
> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
[...]
>  
> +static inline void cpu_set_vmbits(struct cpuinfo_mips *c)
> +{
> +	if (cpu_has_64bits) {
> +		write_c0_entryhi(0xfffffffffffff000ULL);

macro indicated that we need to avoid hazards here on R4000.

Perhaps adding:

  	back_to_back_c0_hazard();

> +		c->vmbits = fls64(read_c0_entryhi() & 0x3ffffffffffff000ULL);
> +	} else
> +		c->vmbits = 32;
> +}
> +