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Re: [Qemu-block] [PATCH v5 7/9] block: don't make snapshots for filters
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-block] [PATCH v5 7/9] block: don't make snapshots for filters |
Date: |
Wed, 16 Nov 2016 07:15:03 -0500 (EST) |
> I've investigated this issue.
> This command line works ok:
> -drive
>
> driver=blkreplay,if=none,image.driver=file,image.filename=testdisk.qcow,id=img-blkreplay
> -device ide-hd,drive=img-blkreplay
>
> And this does not:
> -drive
> driver=blkreplay,if=none,image.driver=qcow2,image.file.driver=file,image.file.filename=testdisk.qcow
> ,id=img-blkreplay
> -device ide-hd,drive=img-blkreplay
>
> QEMU hangs at some moment of replay.
>
> I found that some dma requests do not pass through the blkreplay driver
> due to the following line in block-backend.c:
> return bdrv_co_preadv(blk->root, offset, bytes, qiov, flags);
>
> This line passes read request directly to qcow driver and blkreplay cannot
> process it to make deterministic.
I don't understand, blk->root should be the blkreplay here.
Paolo