Re: [PATCH v3 11/15] MIPS: generic: Add support for Ingenic SoCs

[Guenter Roeck]

On Mon, Oct 12, 2020 at 04:59:01PM +0200, Paul Cercueil wrote:
> Hi Guenter,
> 
> Le lun. 12 oct. 2020 à 7:33, Guenter Roeck <linux@xxxxxxxxxxxx> a écrit :
> > On Sun, Sep 06, 2020 at 09:29:31PM +0200, Paul Cercueil wrote:
> > >  Add support for Ingenic SoCs in arch/mips/generic/.
> > > 
> > >  The Kconfig changes are here to ensure that it is possible to
> > > compile
> > >  either a generic kernel that supports Ingenic SoCs, or a
> > > Ingenic-only
> > >  kernel, both using the same code base, to avoid duplicated code.
> > > 
> > >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> > 
> > This patch results in the following build error (mips:allmodconfig).
> > 
> > In file included from <command-line>:
> > arch/mips/mm/init.c: In function 'mem_init':
> > include/linux/compiler_types.h:319:38: error: call to
> > '__compiletime_assert_331'
> > 	declared with attribute error: BUILD_BUG_ON failed:
> > 		IS_ENABLED(CONFIG_32BIT) && (_PFN_SHIFT > PAGE_SHIFT)
> > 
> > Bisect log attached.
> 
> This doesn't seem to be something that was added with this patch. This
> COMPILE_BUG_ON() has been here for quite some time... I'm not sure why it
> triggers now.
> 
Reverting the offending patch from next-20201009 fixes the problem
(after fixing a context conflict).

> The mips:allmodconfig works here as long as I switch to CPU_LITTLE_ENDIAN
> (no big-endian compiler). But I'm at a different HEAD, and I can't find
> commit d67bc7812221606e1886620a357b13f906814af7 anywhere, in which repo is
> that found?
> 

d67bc7812221606e1886620a357b13f906814af7 is the tip of next-20201009.

The key difference is that the code in linux-next sets
CONFIG_CPU_SUPPORTS_HUGEPAGES=y and enables CONFIG_MIPS_HUGE_TLB_SUPPORT.
This was not previously the case, and was added/enabled with your patch.
As result, _CACHE_SHIFT and with it _PFN_SHIFT is one larger than in
mainline, which seems sufficient to trigger the problem.

Underlying change is that CONFIG_MACH_INGENIC was not set with
mips:allmodconfig prior to your patch, but it is now set.

Guenter

> Cheers,
> -Paul
> 
> > ---
> > # bad: [d67bc7812221606e1886620a357b13f906814af7] Add linux-next
> > specific files for 20201009
> > # good: [549738f15da0e5a00275977623be199fbbf7df50] Linux 5.9-rc8
> > git bisect start 'HEAD' 'v5.9-rc8'
> > # bad: [b71be15b496cc71a3434a198fc1a1b9e08af6c57] Merge remote-tracking
> > branch 'bpf-next/master' into master
> > git bisect bad b71be15b496cc71a3434a198fc1a1b9e08af6c57
> > # bad: [6be11f939f380ef14bc94242cb0262197ce2a054] Merge remote-tracking
> > branch 'i2c/i2c/for-next' into master
> > git bisect bad 6be11f939f380ef14bc94242cb0262197ce2a054
> > # good: [c03a115d8ad8a87b6d275c3c91c13bc111217bf6] Merge remote-tracking
> > branch 'samsung-krzk/for-next' into master
> > git bisect good c03a115d8ad8a87b6d275c3c91c13bc111217bf6
> > # bad: [bdd0ef71b0d7d6a8f1d59af57dc73d19ddc26ad0] Merge remote-tracking
> > branch 'f2fs/dev' into master
> > git bisect bad bdd0ef71b0d7d6a8f1d59af57dc73d19ddc26ad0
> > # bad: [0c4bd40a7ccd06122c1942f525b714abcd9efe36] Merge remote-tracking
> > branch 'powerpc/next' into master
> > git bisect bad 0c4bd40a7ccd06122c1942f525b714abcd9efe36
> > # bad: [744d2c114d58c11fd76d572021d7ef3c55a1a225] Merge remote-tracking
> > branch 'nds32/next' into master
> > git bisect bad 744d2c114d58c11fd76d572021d7ef3c55a1a225
> > # good: [1e9f9330cea616f9f2baf8144f049e4b405715dd] Merge remote-tracking
> > branch 'csky/linux-next' into master
> > git bisect good 1e9f9330cea616f9f2baf8144f049e4b405715dd
> > # bad: [b350041e6f23a71f63f1eee6d939c846838e7e25] MIPS: alchemy: remove
> > unused ALCHEMY_GPIOINT_AU1000
> > git bisect bad b350041e6f23a71f63f1eee6d939c846838e7e25
> > # good: [43df4eb2fc9511e09c66252c3fec4f8933a77c73] MIPS: Replace
> > SIBYTE_1956_WAR by CONFIG_SB1_PASS_2_WORKAROUNDS
> > git bisect good 43df4eb2fc9511e09c66252c3fec4f8933a77c73
> > # good: [13a0ea28e8c698cc0d600fdeed8da3e4d478b97e] MIPS: generic: Init
> > command line with fw_init_cmdline()
> > git bisect good 13a0ea28e8c698cc0d600fdeed8da3e4d478b97e
> > # bad: [d41afc398fbc9dfb8c40b951e97a7f0283346c6a] MAINTAINERS: Update
> > paths to Ingenic platform code
> > git bisect bad d41afc398fbc9dfb8c40b951e97a7f0283346c6a
> > # bad: [f0f4a753079c636d5d43a102edbde0dad1e7de51] MIPS: generic: Add
> > support for Ingenic SoCs
> > git bisect bad f0f4a753079c636d5d43a102edbde0dad1e7de51
> > # good: [c3e2ee657418f4f2bff1269c0550f8135ed0c927] MIPS: generic: Add
> > support for zboot
> > git bisect good c3e2ee657418f4f2bff1269c0550f8135ed0c927
> > # good: [02bd530f888c6d6ba4995c3afcd10f87c136f173] MIPS: generic:
> > Increase NR_IRQS to 256
> > git bisect good 02bd530f888c6d6ba4995c3afcd10f87c136f173
> > # first bad commit: [f0f4a753079c636d5d43a102edbde0dad1e7de51] MIPS:
> > generic: Add support for Ingenic SoCs
> 
>