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From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Antony Pavlov <antonynpavlov@gmail.com>,
	Sascha Hauer <sha@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: RISC-V: erizo: large gap between bss and stack regions
Date: Wed, 14 Apr 2021 13:20:44 +0200	[thread overview]
Message-ID: <5b740bc2-c0a2-2592-557b-f5da2540025f@pengutronix.de> (raw)
In-Reply-To: <20210414140736.bf2d10eed1149d407434575a@gmail.com>

On 14.04.21 13:07, Antony Pavlov wrote:
> On Wed, 14 Apr 2021 11:54:27 +0200
> Sascha Hauer <sha@pengutronix.de> wrote:
> 
>> On Wed, Apr 14, 2021 at 08:54:22AM +0300, Antony Pavlov wrote:
>>> Hi Ahmad!
>>>
>>> Here is the iomem command output on erizo:
>>>
>>> barebox:/ iomem
>>> 0x00000000 - 0xffffffff (size 0x00000000) iomem
>>>   0x80000000 - 0x807fffff (size 0x00800000) ram0
>>>     0x804ffd00 - 0x805ffcff (size 0x00100000) malloc space
>>>     0x805ffd00 - 0x805fffe6 (size 0x000002e7) board data
>>>     0x80600000 - 0x80636b1f (size 0x00036b20) barebox
>>>     0x80636b20 - 0x8063ec9b (size 0x0000817c) barebox data
>>>     0x8063ec9c - 0x80643147 (size 0x000044ac) bss
>>>     0x807e0000 - 0x807fffff (size 0x00020000) stack
>>>   0x90000000 - 0x9000001f (size 0x00000020) 90000000.uart@90000000.of
>>>   0x91000000 - 0x91000003 (size 0x00000004) 91000000.gpio@91000000.of
>>>   0x91000004 - 0x91000007 (size 0x00000004) 91000000.gpio@91000000.of
>>>
>>> I see large unused region between bss and stack regions (>1600 Kbytes).
>>
>> That's normal. The compressed barebox knows the size of the uncompressed
>> barebox, but it doesn't know the size of the bss segment above it. For
>> that reason we have a very pessimistic estimate of:
>>
>> #define MAX_BSS_SIZE SZ_1M
>>
>> The barebox binary itself is then aligned to the previous 1MiB
>> boundary, so barebox usually starts at 2MiB below the end of SDRAM.
>> That's a bit wasteful for boards with very little memory like the erizo,
>> but that's how things are at the moment.
> 
> Can we make it configurable via Kconfig?

Or even better: Could we easily add to the piggy data the size of bss
it contains?

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  reply	other threads:[~2021-04-14 11:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-14  5:54 Antony Pavlov
2021-04-14  9:54 ` Sascha Hauer
2021-04-14 11:07   ` Antony Pavlov
2021-04-14 11:20     ` Ahmad Fatoum [this message]
2021-04-14 12:54       ` Antony Pavlov
2021-04-14 12:58         ` Sascha Hauer
2021-04-15  7:54       ` Sascha Hauer

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