linux-kernel - RE: [PATCHv1 04/12] unicore32 core architecture: low level entry and setup code

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Date:	Mon, 10 Jan 2011 19:26:11 +0800
From:	"Guan Xuetao" <guanxuetao@...c.pku.edu.cn>
To:	"'Arnd Bergmann'" <arnd@...db.de>
Cc:	<linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: RE: [PATCHv1 04/12] unicore32 core architecture: low level entry and setup code



> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@...db.de]
> Sent: Friday, January 07, 2011 8:05 AM
> To: Guan Xuetao
> Cc: linux-arch@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCHv1 04/12] unicore32 core architecture: low level entry and setup code
> 
> On Saturday 25 December 2010, Guan Xuetao wrote:
> > +#ifdef __KERNEL__
> > +
> > +/*
> > + * Memory map description
> > + */
> > +# define NR_BANKS 8
> > +
> > +struct membank {
> > +	unsigned long start;
> > +	unsigned long size;
> > +	unsigned int highmem;
> > +};
> > +
> > +struct meminfo {
> > +	int nr_banks;
> > +	struct membank bank[NR_BANKS];
> > +};
> > +
> > +extern struct meminfo meminfo;
> > +
> > +#define for_each_bank(iter, mi)				\
> > +	for (iter = 0; iter < (mi)->nr_banks; iter++)
> > +
> > +#define bank_pfn_start(bank)	__phys_to_pfn((bank)->start)
> > +#define bank_pfn_end(bank)	__phys_to_pfn((bank)->start + (bank)->size)
> > +#define bank_pfn_size(bank)	((bank)->size >> PAGE_SHIFT)
> > +#define bank_phys_start(bank)	((bank)->start)
> > +#define bank_phys_end(bank)	((bank)->start + (bank)->size)
> > +#define bank_phys_size(bank)	((bank)->size)
> 
> The membank stuff looks like a variation of the generic memblock interfaces.
Memblock  codes came from arm,  and I can only find similar definitions in arm, unicore32,
and perhaps xtensa's sysmem_info.
So, I suggest an empty memblock.h is preferred, and perhaps more architectures could use it.

> 
> > +/*
> > + * Handle all unrecognised system calls.
> > + *  0x9f0000 - 0x9fffff are some more esoteric system calls
> > + */
> > +#define NR(x) ((__UNICORE_NR_##x) - __UNICORE_NR_BASE)
> > +asmlinkage int uc32_syscall(int no, struct pt_regs *regs)
> > +{
> > +	if ((no >> 16) != (__UNICORE_NR_BASE >> 16))
> > +		return -ENOSYS;
> > +
> > +	switch (no & 0xffff) {
> > +	/*
> > +	 * Flush a region from virtual address 'r0' to virtual address 'r1'
> > +	 * _exclusive_.  There is no alignment requirement on either address;
> > +	 * user space does not need to know the hardware cache layout.
> > +	 *
> > +	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
> > +	 * is defined to be something else.  For now we ignore it, but may
> > +	 * the fires of hell burn in your belly if you break this rule. ;)
> > +	 *
> > +	 * (at a later date, we may want to allow this call to not flush
> > +	 * various aspects of the cache.  Passing '0' will guarantee that
> > +	 * everything necessary gets flushed to maintain consistency in
> > +	 * the specified region).
> > +	 */
> > +	case NR(cacheflush):
> > +		do_cache_op(regs->UCreg_00, regs->UCreg_01, regs->UCreg_02);
> > +		return 0;
> > +
> > +	case NR(cmpxchg):
> > +		return do_cmpxchg_op(regs);
> > +
> > +	default:
> > +		return -ENOSYS;
> > +	}
> > +}
> 
> With the generic system cal interface, this function should be replaced
> with straight system calls for each of the subfunctions.
> 
> Just use things definitions like
> 
> #define __NR_cacheflush __NR_arch_specific_syscall
> __SYSCALL(__NR_cacheflush, sys_uc32_cacheflush)
> #define __NR_cmpxchg __NR_arch_specific_syscall+1
> __SYSCALL(__NR_cmpxchg, sys_uc32_cacheflush
> 
> in your asm/unistd.h file.
Yes. Thanks. It's high time to do this work for me.

Guan Xuetao


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