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Date:      Sun, 29 Dec 2019 14:38:20 -0800
From:      Mark Millard <marklmi@yahoo.com>
To:        Hans Petter Selasky <hps@selasky.org>
Cc:        FreeBSD Current <freebsd-current@freebsd.org>, freebsd-hackers@freebsd.org, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>
Subject:   Re: head -r356109 on 32-bit powerpc (old PowerMac): Memory modified after free during late-stage of boot, most recently used by bus-sc
Message-ID:  <558A986F-B0C9-447A-A569-4D90A2B44C58@yahoo.com>
In-Reply-To: <42bf7ff5-1279-28cb-5b4b-a0335e819a3a@selasky.org>
References:  <28FD8632-AC91-40D7-B6E7-36E304D37794.ref@yahoo.com> <28FD8632-AC91-40D7-B6E7-36E304D37794@yahoo.com> <42bf7ff5-1279-28cb-5b4b-a0335e819a3a@selasky.org>

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On 2019-Dec-29, at 14:04, Hans Petter Selasky <hps at selasky.org> =
wrote:

> On 2019-12-29 22:53, Mark Millard via freebsd-hackers wrote:
>> 0xd2630510: at uma_zalloc_arg+0x1b4
>> 0xd2630540: at malloc+0xfc
>> 0xd2630580: at alloc_bounce_pages+0x7c
>> 0xd26305c0: at bus_dmamap_create+0x1e8
>=20
> Do you know what drivers are using bounce pages?

No clue. Looking around a bit I see that there is:

        if (newtag->lowaddr < ptoa((vm_paddr_t)Maxmem) && newtag->iommu =
=3D=3D NULL)
                newtag->flags |=3D BUS_DMA_COULD_BOUNCE;

        if (newtag->alignment > 1)
                newtag->flags |=3D BUS_DMA_COULD_BOUNCE;

in bus_dma_tag_create (in sys/powerpc/powerpc/busdma_machdep.c ).
But that does not indicate what all specifically might have met
one of those 2 conditions for some tag creation. (The material
is not familiar.)


=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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