On Tue, Dec 13, 2016 at 08:40:00AM -0800, Andy Lutomirski wrote:
> But I think this is rather silly. Joerg, Linus, etc: would it be okay
> to change lib/dma-debug.c to allow DMA *from* rodata?
Yeah, this would be fine for DMA_TO_DEVICE mappings. At least I can't
think of a reason right now to not
Andy Lutomirski wrote:
> I don't know whether you're right, but that sounds a bit silly to me.
> This is a *tiny* amount of memory.
Assuming a 1MiB kernel image in 4K pages, that gets you back a couple of pages
I think - useful if you've only got a few MiB of RAM.
David
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On Tue, Dec 13, 2016 at 8:45 AM, David Howells wrote:
> Andy Lutomirski wrote:
>
>> After all, rodata is ordinary memory, is backed by struct page, etc.
>
> Is that actually true? I thought some arches excluded the kernel image from
> the page struct array to make the array consume less memory.
Andy Lutomirski wrote:
> After all, rodata is ordinary memory, is backed by struct page, etc.
Is that actually true? I thought some arches excluded the kernel image from
the page struct array to make the array consume less memory.
David
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On Tue, Dec 13, 2016 at 4:20 AM, David Laight wrote:
> From: Andy Lutomirski
>> Sent: 12 December 2016 20:53
>> The driver put a constant buffer of all zeros on the stack and
>> pointed a scatterlist entry at it in two places. This doesn't work
>> with virtual st
From: Andy Lutomirski
> Sent: 12 December 2016 20:53
> The driver put a constant buffer of all zeros on the stack and
> pointed a scatterlist entry at it in two places. This doesn't work
> with virtual stacks. Use a static 16-byte buffer of zeros instead.
...
I didn't think you could dma from st
On Mon, Dec 12, 2016 at 2:28 PM, David Howells wrote:
> Andy Lutomirski wrote:
>
>> +static const char zero_pad[16] = {0};
>
> Isn't there a global page of zeros or something that we can share? Also, you
> shouldn't explicitly initialise it so that it stays in .bss.
This is a double-edged sword
Andy Lutomirski wrote:
> +static const char zero_pad[16] = {0};
Isn't there a global page of zeros or something that we can share? Also, you
shouldn't explicitly initialise it so that it stays in .bss.
> - sg_set_buf(&sg_out[1], pad, sizeof pad);
> + sg_set_buf(&sg_out[1], zero_pad, si
The driver put a constant buffer of all zeros on the stack and
pointed a scatterlist entry at it in two places. This doesn't work
with virtual stacks. Use a static 16-byte buffer of zeros instead.
Cc: sta...@vger.kernel.org # 4.9 only
Reported-by: Eric Biggers
Signed-off-by: Andy Lutomirski
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