From: Mike Rapoport <rppt@linux.ibm.com>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Yash Shah <yash.shah@sifive.com>,
"Paul Walmsley ( Sifive)" <paul.walmsley@sifive.com>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"palmer@dabbelt.com" <palmer@dabbelt.com>,
"aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
"Anup.Patel@wdc.com" <Anup.Patel@wdc.com>,
"ren_guo@c-sky.com" <ren_guo@c-sky.com>,
"bmeng.cn@gmail.com" <bmeng.cn@gmail.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
Sachin Ghadi <sachin.ghadi@sifive.com>
Subject: Re: [PATCH] RISC-V: Add address map dumper
Date: Mon, 11 Nov 2019 22:55:28 +0100 [thread overview]
Message-ID: <20191111215527.GA10647@linux.ibm.com> (raw)
In-Reply-To: <91f35033-ffc8-cd2e-36f7-c6f4f25be36b@deltatee.com>
On Mon, Nov 11, 2019 at 11:14:30AM -0700, Logan Gunthorpe wrote:
>
>
> On 2019-11-10 10:27 p.m., Yash Shah wrote:
> > Add support for dumping the kernel address space layout to the console.
> > User can enable CONFIG_DEBUG_VM_LAYOUT to dump the virtual memory region
> > into dmesg buffer during boot-up.
>
> Cool, I'd find this useful. Though, is there any reason we don't do this
> more generally for all architectures?
Some architectures do this, some don't. I don't think there's a particular
reason we don't do this generally, it just evolved that way :)
> > Signed-off-by: Yash Shah <yash.shah@sifive.com>
> > ---
> > This patch is based on Linux 5.4-rc6 and tested on SiFive HiFive Unleashed
> > board.
> > ---
> > arch/riscv/Kconfig.debug | 9 +++++++++
> > arch/riscv/mm/init.c | 30 ++++++++++++++++++++++++++++++
> > 2 files changed, 39 insertions(+)
> >
> > diff --git a/arch/riscv/Kconfig.debug b/arch/riscv/Kconfig.debug
> > index e69de29..cdedfd3 100644
> > --- a/arch/riscv/Kconfig.debug
> > +++ b/arch/riscv/Kconfig.debug
> > @@ -0,0 +1,9 @@
> > +config DEBUG_VM_LAYOUT
> > + bool "Print virtual memory layout on boot up"
> > + depends on DEBUG_KERNEL
> > + help
> > + Say Y here if you want to dump the kernel virtual memory layout to
> > + dmesg log on boot up. This information is only useful for kernel
> > + developers who are working in architecture specific areas of the
> > + kernel. It is probably not a good idea to enable this feature in a
> > + production kernel.
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 79cfb35..fcb8144 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -55,6 +55,36 @@ void __init mem_init(void)
> > memblock_free_all();
> >
> > mem_init_print_info(NULL);
> > +#ifdef CONFIG_DEBUG_VM_LAYOUT
>
> Generally, it's best to avoid #ifdefs inside functions, it's even
> counter-indicated in the style guide[1].
>
> > +#define MLK(b, t) b, t, (((t) - (b)) >> 10)
> > +#define MLM(b, t) b, t, (((t) - (b)) >> 20)
> > +#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
>
> I personally find these inline defines rather ugly. Maybe it would be
> better to have a helper function that prints a single line. Also seems
> like MLK and MLK_ROUNDUP could be the same assuming the entries in MLK
> are aligned...
>
> > +
> > + pr_notice("Virtual kernel memory layout:\n"
> > + " fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n"
> > + " vmemmap : 0x%08lx - 0x%08lx (%4ld MB)\n"
> > + " vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n"
> > + " lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n"
> > + " .init : 0x%px - 0x%px (%4td kB)\n"
> > + " .text : 0x%px - 0x%px (%4td kB)\n"
> > + " .data : 0x%px - 0x%px (%4td kB)\n"
> > + " .bss : 0x%px - 0x%px (%4td kB)\n",
> > +
> > + MLK(FIXADDR_START, FIXADDR_TOP),
> > + MLM(VMEMMAP_START, VMEMMAP_END),
> > + MLM(VMALLOC_START, VMALLOC_END),
> > + MLM(PAGE_OFFSET, (unsigned long)high_memory),
> > +
> > + MLK_ROUNDUP(__init_begin, __init_end),
> > + MLK_ROUNDUP(_text, _etext),
> > + MLK_ROUNDUP(_sdata, _edata),
> > + MLK_ROUNDUP(__bss_start, __bss_stop));
> > +
> > +#undef MLK
> > +#undef MLM
> > +#undef MLK_ROUNDUP
> > +#endif
> > }
> >
> > #ifdef CONFIG_BLK_DEV_INITRD
>
> Thanks,
>
> Logan
>
> [1]
> https://www.kernel.org/doc/html/latest/process/coding-style.html#conditional-compilation
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2019-11-11 21:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-11 5:27 [PATCH] RISC-V: Add address map dumper Yash Shah
2019-11-11 18:14 ` Logan Gunthorpe
2019-11-11 21:55 ` Mike Rapoport [this message]
2019-11-12 6:19 ` Yash Shah
2019-11-11 21:56 ` Mike Rapoport
2019-11-12 6:35 ` Yash Shah
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