From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Date: Wed, 28 Oct 2020 18:57:41 +0000 Subject: Re: [PATCH 11/13] m68k/mm: make node data and node setup depend on CONFIG_DISCONTIGMEM Message-Id: <20201028185741.GI1428094@kernel.org> List-Id: References: <20201027112955.14157-1-rppt@kernel.org> <20201027112955.14157-12-rppt@kernel.org> <20201028111631.GF1428094@kernel.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Michael Schmitz Cc: Geert Uytterhoeven , Andrew Morton , Alexey Dobriyan , Catalin Marinas , Greg Ungerer , John Paul Adrian Glaubitz , Jonathan Corbet , Matt Turner , Meelis Roos , Mike Rapoport , Russell King , Tony Luck , Vineet Gupta , Will Deacon , alpha , Linux ARM , "open list:DOCUMENTATION" , Linux FS Devel , "linux-ia64@vger.kernel.org" , Linux Kernel Mailing List , linux-m68k , Linux MM , arcml On Thu, Oct 29, 2020 at 07:14:38AM +1300, Michael Schmitz wrote: > Hi Mike, >=20 > On 29/10/20 12:16 AM, Mike Rapoport wrote: > > Hi Geert, > >=20 > > On Wed, Oct 28, 2020 at 10:25:49AM +0100, Geert Uytterhoeven wrote: > > > Hi Mike, > > >=20 > > > On Tue, Oct 27, 2020 at 12:31 PM Mike Rapoport wrot= e: > > > > From: Mike Rapoport > > > >=20 > > > > The pg_data_t node structures and their initialization currently de= pends on > > > > !CONFIG_SINGLE_MEMORY_CHUNK. Since they are required only for DISCO= NTIGMEM > > > > make this dependency explicit and replace usage of > > > > CONFIG_SINGLE_MEMORY_CHUNK with CONFIG_DISCONTIGMEM where appropria= te. > > > >=20 > > > > The CONFIG_SINGLE_MEMORY_CHUNK was implicitly disabled on the ColdF= ire MMU > > > > variant, although it always presumed a single memory bank. As there= is no > > > > actual need for DISCONTIGMEM in this case, make sure that ColdFire = MMU > > > > systems set CONFIG_SINGLE_MEMORY_CHUNK to 'y'. > > > >=20 > > > > Signed-off-by: Mike Rapoport > > > Thanks for your patch! > > >=20 > > > > --- > > > > arch/m68k/Kconfig.cpu | 6 +++--- > > > > arch/m68k/include/asm/page_mm.h | 2 +- > > > > arch/m68k/mm/init.c | 4 ++-- > > > > 3 files changed, 6 insertions(+), 6 deletions(-) > > > Is there any specific reason you didn't convert the checks for > > > CONFIG_SINGLE_MEMORY_CHUNK in arch/m68k/kernel/setup_mm.c > > In arch/m68k/kernel/setup_mm.c the CONFIG_SINGLE_MEMORY_CHUNK is needed > > for the case when a system has two banks, the kernel is loaded into the > > second bank and so the first bank cannot be used as normal memory. It > > does not matter what memory model will be used in this case. >=20 >=20 > That case used to be detected just fine at run time (by dint of the second > memory chunk having an address below the first; the chunk the kernel resi= des > in is always listed first), even without using CONFIG_SINGLE_MEMORY_CHUNK. =20 Right, CONFIG_SINGLE_MEMORY_CHUNK in arch/m68k/kernel/setup_mm.c is used to force using a single bank of memory regardless of run time detection.=20 > Unless you changed that behaviour (and I see nothing in your patch that > would indicate that), this is still true. >=20 > Converting the check as Geert suggested, without also adding a test for > out-of-order memory bank addresses, would implicitly treat DISCONTIGMEM a= s=A0 > SINGLE_MEMORY_CHUNK, regardless of bank ordering. I don't think that is w= hat > we really want? It is in a way the case now when !SINGLE_MEMORY_CHUNK =3D DISCONTIGMEM. So forcing SIGNLE_MEMORY_CHUNK at compile time would also mean forcing FLATMEM. After these changes I think SINGLE_MEMORY_CHUNK is not needed at all. > Cheers, >=20 > =A0=A0=A0 Michael >=20 >=20 > >=20 > > > and arch/m68k/include/asm/virtconvert.h? > > I remember I had build errors and troubles with include file > > dependencies if I changed it there, but I might be mistaken. I'll > > recheck again. > >=20 > > > Gr{oetje,eeting}s, > > >=20 > > > Geert > > >=20 > > > --=20 > > > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linu= x-m68k.org > > >=20 > > > In personal conversations with technical people, I call myself a hack= er. But > > > when I'm talking to journalists I just say "programmer" or something = like that. > > > -- Linus Torvalds --=20 Sincerely yours, Mike.