linux-kernel - Re: [PATCH 04/14] x86, ACPI: make acpi override finding work with 32bit flat mode

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Message-ID: <CAE9FiQVXOC71BGSK3t_xg+nP5Qq8ZKoup0sTMJDPnv-y8++=hg@mail.gmail.com>
Date:	Thu, 7 Mar 2013 22:57:21 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Tejun Heo <tj@...nel.org>, "Yu, Fenghua" <fenghua.yu@...el.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Renninger <trenn@...e.de>,
	Tang Chen <tangchen@...fujitsu.com>,
	linux-kernel@...r.kernel.org, Pekka Enberg <penberg@...nel.org>,
	Jacob Shin <jacob.shin@....com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-acpi@...r.kernel.org
Subject: Re: [PATCH 04/14] x86, ACPI: make acpi override finding work with
 32bit flat mode

On Thu, Mar 7, 2013 at 9:50 PM, Tejun Heo <tj@...nel.org> wrote:
> On Thu, Mar 07, 2013 at 08:58:30PM -0800, Yinghai Lu wrote:
>> We will find acpi tables in initrd during head_32.S in 32bit flat mode.
>>
>> So need acpi_initrd_override_find could take phys directly.
>
> The patch description doesn't explain even half of what's going on.

hope HPA could understand.

Access initrd before relocate_initrd and init_memory mapping.

>
>> @@ -552,38 +552,47 @@ u8 __init acpi_table_checksum(u8 *buffer, u32 length)
>>       return sum;
>>  }
>>
>> -/* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
>> -static const char * const table_sigs[] = {
>> -     ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ,
>> -     ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT,
>> -     ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF,
>> -     ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET,
>> -     ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI,
>> -     ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
>> -     ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
>> -     ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
>> -     ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, NULL };
>
> Why is this table made a stack variable?  What's the benefit of doing
> that?

so I do need to switch global variables to phys and access it.

>
>>  /* Non-fatal errors: Affected tables/files are ignored */
>>  #define INVALID_TABLE(x, path, name)                                 \
>> -     { pr_err("ACPI OVERRIDE: " x " [%s%s]\n", path, name); continue; }
>> +     do { pr_err("ACPI OVERRIDE: " x " [%s%s]\n", path, name); } while (0)
>
> Might as well rename the macro to something which indicates it's just
> printing error message.  Urgh... who thought embedding control flow
> directive like continue inside a macro was a good idea? :(

so I removed it.

>
>> -void __init acpi_initrd_override_find(void *data, size_t size)
>> +void __init acpi_initrd_override_find(void *data, size_t size, bool is_phys)
>
> Is it really necessary to make the function take both virtual and
> physical addresses?  Can't we just make the function take phys_addr_t
> and update everyone to call with physaddr?  Also @is_phys isn't simple
> address switch.  It also changes error reporting.  If you're gonna
> keep @is_phys, let's at least write up a function comment explaining
> what's going on and why we need it.  But, really, if at all possible,
> let's change the function to take single type of argument and
> predicate error message printing on something else (e.g. early printk
> initialized or whatever).

yes, one for 32bit from head_32.S, phys.
one for 64bit from head64.c. with _va.

Not sure if I could use early_printk from head_32.S, as Fenghua does
not print out
from microcode updating early in the same parts.

Will check that.

>
>> @@ -654,11 +677,14 @@ void __init acpi_initrd_override_copy(void)
>>       arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
>>
>>       for (no = 0; no < table_nr; no++) {
>> +             unsigned long phys_addr = (unsigned long)early_initrd_files[no].data;
>
> Can we please use phys_addr_t for physical addresses?

ok.

>
>>               unsigned long size = early_initrd_files[no].size;
>>
>> +             q = early_ioremap(phys_addr, size);
>> +             pr_info("%4.4s ACPI table found in initrd [%#010lx-%#010lx]\n",
>> +                             ((struct acpi_table_header *)q)->signature,
>> +                             phys_addr, phys_addr + size - 1);
>
> Maybe putting pr_info after ioremapping both p and q would be easier
> on the eyes?

ok.

>
>>               p = early_ioremap(acpi_tables_addr + total_offset, size);
>> -             q = early_ioremap((unsigned long)early_initrd_files[no].data,
>> -                                      size);
>>               memcpy(p, q, size);
>>               early_iounmap(q, size);
>>               early_iounmap(p, size);

Thanks

Yinghai
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