Re: [PATCH 3/4] ARM: change vmalloc_min to vmalloc_start

Linus Walleij
2021-05-18T22:20:16Z

On Tue, May 18, 2021 at 2:15 PM Russell King (Oracle)
<rmk+kernel@armlinux.org.uk> wrote:

> Change the current vmalloc_min, which is supposed to be the lowest
> address of vmalloc space including the VMALLOC_OFFSET, to vmalloc_start
> which does not include VMALLOC_OFFSET.
>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

> +static unsigned long __initdata vmalloc_start = VMALLOC_END - (240 << 20);

When I first read this it took me some time to figure out what was
going on here, so if you have time, please fold in a comment
with some explanation of that (240 << 20) thing, in some blog
post I described it as "an interesting way to write 0x0f000000"
but I suppose commit 0536bdf33faf chose this way for a
specific reason? (Paging Nico if he can explain it.)

Yours,
Linus Walleij