Re: [PATCH v1] MIPS: remove .bss to __rel_start overlay

[Oleksij Rempel <o.rempel@pengutronix.de>]

On 28.01.20 14:43, Oleksij Rempel wrote:
> 
> 
> On 28.01.20 14:06, Peter Mamonov wrote:
>> On Tue, Jan 28, 2020 at 02:55:13PM +0300, Antony Pavlov wrote:
>>> On Tue, 28 Jan 2020 10:28:32 +0100
>>> Oleksij Rempel <o.rempel@pengutronix.de> wrote:
>>>
>>> Hi!
>>>
>>> Looks like this patch has some undocummented side effects
>>> (or in other words, it makes undocummented fixups).
>>>
>>> I have tested this patch on qemu-malta with current master,
>>> ee8960aec018df2de ("ARM: imx6: properly check for IPU presence").
>>> It works fine: memtest works, iomem output looks good.
>>>
>>> But the patch fixes several issues and commit message does not contain
>>> any information about it.
>>>
>>> I rebuild current master with qemu-malta_defconfig and MMU enabled.
>>>
>>> I used this qemu cmdline to enable qemu monitor:
>>>
>>> qemu-system-mips -nodefaults -M malta -m 256 -nographic -bios barebox-flash-image
>>>     -net user -net nic,model=rtl8139 -serial mon:stdio
>>>
>>> With '-serial mon:stdio' one can invoke qemu monitor with "ctrl-a c" keypress sequence.
>>>
>>> So I tried 'info registers' qemu monitor command after barebox startup:
>>>
>>> Hit any to stop autoboot:    3
>>> barebox@qemu malta:/
>>> barebox@qemu malta:/
>>> barebox@qemu malta:/ iomem
>>> 0x00000000 - 0xffffffff (size 0x00000000) iomem
>>>    0x180003f8 - 0x180003ff (size 0x00000008) 180003f8.serial@180003f8.of
>>>    0x1e000000 - 0x1e3fffff (size 0x00400000) 1e000000.flash@1e000000.of
>>>    0x1f000900 - 0x1f00093f (size 0x00000040) 1f000900.serial@1f000900.of
>>>    0x1f000b00 - 0x1f000b1f (size 0x00000020) 1f000b00.gpio@1f000b00.of
>>>    0x80000000 - 0x8fffffff (size 0x10000000) kseg0_ram0
>>> barebox@qemu malta:/ QEMU 4.2.0 monitor - type 'help' for more information
>>> (qemu) info registers
>>> pc=0xa081232c HI=0x00000026 LO=0x20000000 ds 0090 a081232c 1
>>> GPR00: r0 00000000 at 00000000 v0 b80003f8 v1 00000000
>>> GPR04: a0 a0408668 a1 b80003fd a2 b80003f8 a3 ffffffff
>>> GPR08: t0 00000001 t1 00000000 t2 0000005a t3 00000023
>>> GPR12: t4 00000000 t5 00010000 t6 00000040 t7 00000010
>>> GPR16: s0 a0408668 s1 a085cd20 s2 a0860000 s3 a0860000
>>> GPR20: s4 a0860000 s5 00000400 s6 a08613c0 s7 00000001
>>> GPR24: t8 00000008 t9 a0812340 k0 00400000 k1 fffffffa
>>> GPR28: gp 00000000 sp 8fb8fd10 s8 ffffffff ra a0812420
>>> CP0 Status  0x00000000 Cause   0x00000400 EPC    0x00000000
>>>      Config0 0x80008482 Config1 0x9e190c8f LLAddr 0x0000000000000000
>>>      Config2 0x80000000 Config3 0x00000000
>>>      Config4 0x00000000 Config5 0x00000000
>>> (qemu) quit
>>>
>>> So I see several issues in current master at once:
>>>
>>>    * iomem output has no information on sdram regions, so memtest is unusable;
>>>    * pc=0xa081232c, relocation does not work, barebox is located with 8M offset
>>>      from start of RAM. The board has 256M and relocation routine
>>>      should move barebox code much higher;
>>>    * pc=0xa081232c, so barebox code works from KSEG1 not from KSEG0 as MMU=y option 
>>> implies.
>>>
>>> Your patch fixes all these symptoms at ones however the commit message
>>> says nothing about them.
>>
>> I've tested the patch, everything looks right now:
>>
>>     barebox@qemu malta:/ iomem
>>     0x00000000 - 0xffffffff (size 0x00000000) iomem
>>       0x180003f8 - 0x180003ff (size 0x00000008) 180003f8.serial@180003f8.of
>>       0x1e000000 - 0x1e3fffff (size 0x00400000) 1e000000.flash@1e000000.of
>>       0x1f000900 - 0x1f00093f (size 0x00000040) 1f000900.serial@1f000900.of
>>       0x1f000b00 - 0x1f000b1f (size 0x00000020) 1f000b00.gpio@1f000b00.of
>>       0x80000000 - 0x8fffffff (size 0x10000000) kseg0_ram0
>>         0x8fb89000 - 0x8fb8ffff (size 0x00007000) stack
>>         0x8fb90000 - 0x8ff8ffff (size 0x00400000) malloc space
>>         0x8ff90000 - 0x8ffeae9f (size 0x0005aea0) barebox
>>         0x8ffeaea0 - 0x8ffefadf (size 0x00004c40) barebox data
>>         0x8fff7ae0 - 0x8fffbbdf (size 0x00004100) bss
>>     barebox@qemu malta:/ whereami
>>     code   @ 8ffb9bcc (8ffb9bc0)
>>     data   @ 8ffef3c0
>>     bss    @ 8fff9ae0
>>     heap   @ 8fbb9518
>>     stack  @ 8fb8fd50
>>     barebox@qemu malta:/
>>
>> However I have to enable CONFIG_MMU after `make qemu-malta_defconfig`, or I get
>> `ERROR: Error: Cannot request SDRAM region for stack`, and no barebox memory
>> areas in `iomem` output.  CONFIG_MMU seems to be enabled for ath79 only:
>>
>>     $ git grep CONFIG_MMU arch/mips/configs/
>>     arch/mips/configs/ath79_defconfig:CONFIG_MMU=y
>>     $
> 
> Yes, this should be fixed in a separate patch.

Note:
memtest on ar9331 works only with this patch:

diff --git a/arch/mips/lib/cpu-probe.c b/arch/mips/lib/cpu-probe.c
index cbde43a595..0d2dcf8b03 100644
--- a/arch/mips/lib/cpu-probe.c
+++ b/arch/mips/lib/cpu-probe.c
@@ -177,6 +177,9 @@ static int mips_request_stack(void)
         if (!request_sdram_region("stack", mips_stack_top - STACK_SIZE, STACK_SIZE))
                 pr_err("Error: Cannot request SDRAM region for stack\n");

+       if (!request_sdram_region("vector", 0x80000000, 0x8000))
+               pr_err("Error: Cannot request SDRAM region for vector\n");
+
         return 0;
  }
  coredevice_initcall(mips_request_stack);


Kind regards,
Oleksij Rempel

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