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Replace MTD flash drives with PMEM drives #32

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merged 2 commits into from
Oct 10, 2023
Merged

Replace MTD flash drives with PMEM drives #32

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232eed1
feat: replace MTD flash drives with PMEM drives
edubart Jul 14, 2023
bed47c6
feat: trust bootloader rng and enable hugetlbfs support
edubart Jul 25, 2023
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3 changes: 2 additions & 1 deletion configs/default-linux-config
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ CONFIG_VIRTIO_NET=y
CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
CONFIG_HVC_RISCV_SBI=y
# CONFIG_HW_RANDOM is not set
# CONFIG_RANDOM_TRUST_BOOTLOADER is not set
CONFIG_RANDOM_TRUST_BOOTLOADER=y
# CONFIG_HWMON is not set
# CONFIG_USB_SUPPORT is not set
CONFIG_VIRTIO_MMIO=y
Expand All @@ -55,6 +55,7 @@ CONFIG_EXT2_FS_SECURITY=y
CONFIG_EXT4_FS=y
# CONFIG_PROC_PAGE_MONITOR is not set
CONFIG_TMPFS=y
CONFIG_HUGETLBFS=y
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Doesn't this screw with our TLB implementation?

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@edubart edubart Oct 6, 2023 •
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No problems with this, we can use 2MB pages without problems even while only supporting 4KB pages in our TLB, because we have a conservative implementation of TLB that shootdown more than it could. And I already have tested this for a while now.

Actually this config is orthogonal to this PR and the init system, but it is used in World Arcade, and other dapps I am coding. I think we should enable this by default because it enables a way to map fixed physical pages to virtual memory in userspace with minimal overhead, useful for some advanced dapps that needs to write/read to programs in userspace from outside.

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Using huge pages for this feels like a hack. You could use UIO for this instead.

  • You can have physically mapped memory into you dapp, emulator defines to where (via dtb).
  • Optionally have multiple separate regions.
  • Of arbitrary sizes.

It requires a dtb entry and the CONFIG_UIO and CONFIG_UIO_PDRV_GENIRQ kernel configs.

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It is a hack until we have a better way to do this, could be with custom DTB entries like you said, but this will require a new emulator feature to insert custom entries in DTB.

# CONFIG_MISC_FILESYSTEMS is not set
# CONFIG_NETWORK_FILESYSTEMS is not set
CONFIG_LSM="lockdown,yama,loadpin,safesetid,integrity"
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