> -----Original Message----- > From: Catalin Marinas [mailto:catalin.mari...@arm.com] > Sent: Thursday, December 04, 2014 8:03 PM > To: Russell King - ARM Linux > Cc: Wang, Yalin; 'linux...@kvack.org'; Will Deacon; 'linux- > ker...@vger.kernel.org'; 'linux-arm-ker...@lists.infradead.org'; 'linux- > arm-...@vger.kernel.org'; Peter Maydell > Subject: Re: [RFC v2] arm:extend the reserved mrmory for initrd to be page > aligned > > On Mon, Sep 15, 2014 at 12:33:25PM +0100, Russell King - ARM Linux wrote: > > On Mon, Sep 15, 2014 at 07:07:20PM +0800, Wang, Yalin wrote: > > > @@ -636,6 +646,11 @@ static int keep_initrd; void > > > free_initrd_mem(unsigned long start, unsigned long end) { > > > if (!keep_initrd) { > > > + if (start == initrd_start) > > > + start = round_down(start, PAGE_SIZE); > > > + if (end == initrd_end) > > > + end = round_up(end, PAGE_SIZE); > > > + > > > poison_init_mem((void *)start, PAGE_ALIGN(end) - start); > > > free_reserved_area((void *)start, (void *)end, -1, "initrd"); > > > } > > > > is the only bit of code you likely need to achieve your goal. > > > > Thinking about this, I think that you are quite right to align these. > > The memory around the initrd is defined to be system memory, and we > > already free the pages around it, so it *is* wrong not to free the > > partial initrd pages. > > Actually, I think we have a problem, at least on arm64 (raised by Peter > Maydell). There is no guarantee that the page around start/end of initrd is > free, it may contain the dtb for example. This is even more obvious when we > have a 64KB page kernel (the boot loader doesn't know the page size that > the kernel is going to use). > > The bug was there before as we had poison_init_mem() already (not it > disappeared since free_reserved_area does the poisoning). > > So as a quick fix I think we need the rounding the other way (and in the > general case we probably lose a page at the end of initrd): > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index > 494297c698ca..39fd080683e7 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -335,9 +335,9 @@ void free_initrd_mem(unsigned long start, unsigned long > end) { > if (!keep_initrd) { > if (start == initrd_start) > - start = round_down(start, PAGE_SIZE); > + start = round_up(start, PAGE_SIZE); > if (end == initrd_end) > - end = round_up(end, PAGE_SIZE); > + end = round_down(end, PAGE_SIZE); > > free_reserved_area((void *)start, (void *)end, 0, "initrd"); > } > > A better fix would be to check what else is around the start/end of initrd. I think a better way is add some head info in Image header, So that bootloader can know the kernel CONFIG_PAGE_SIZE , For example we can add PAGE_SIZE in zImage header . How about this way?
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