Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 19 Jan 2023 22:21:27 +0530 | Subject | Re: [PATCH V0 1/1] bootconfig: Increase max size of bootconfig from 32 KB to 256 KB for DCC support | From | Souradeep Chowdhury <> |
| |
On 1/12/2023 12:31 PM, Masami Hiramatsu (Google) wrote: > On Tue, 10 Jan 2023 20:38:54 +0530 > Souradeep Chowdhury <quic_schowdhu@quicinc.com> wrote: > >> >> >> On 1/10/2023 8:16 PM, Masami Hiramatsu (Google) wrote: >>> On Tue, 10 Jan 2023 17:26:07 +0530 >>> Souradeep Chowdhury <quic_schowdhu@quicinc.com> wrote: >>> >>>> >>>> >>>> On 1/9/2023 8:48 PM, Masami Hiramatsu (Google) wrote: >>>>> On Mon, 9 Jan 2023 20:01:05 +0530 >>>>> Souradeep Chowdhury <quic_schowdhu@quicinc.com> wrote: >>>>> >>>>>> Increasing the memory size of bootconfig to be able to handle a max number of >>>>>> 8192 nodes to be fitted in memory size of 256KB. >>>>> >>>>> Sorry, but you missed the 'xbc_node::data' stores the index of the data and >>>>> that is uint16_t. So the XBC_DATA_MAX is fixed limitation. >>>>> >>>>> The number of nodes (XBC_NODE_MAX) can be expanded because I just decided it >>>>> to keep the pre-compiled array size ~8KB. Maybe expanding it to 64KB just >>>>> increase the size of kernel on init memory (and freed after boot). >>>>> >>>>> Could you tell me why you need such a big data for your DCC? >>>>> >>>>> Thank you, >>>> >>>> DCC is a debugging tool used in qcom which is needed to debug crashes >>>> that can happen at boot-time. For debugging purposes a large number of >>>> registers need to be configured in DCC driver which is to be fed via the >>>> bootconfig file. For that we need to expand the nodes as well as memory >>>> for using bootconfig. >>> >>> Hmm, how many registers does DCC usually use? And how big the bootconfig >>> file is usually? I have no idea about that. >> >> So a typical bootconfig file for consumption of DCC looks like as follows >> >> dcc_config { >> link_list_0 { >> qcom-curr-link-list = 6 >> qcom-link-list = R_0x1781005c_1_apb, >> R_0x1782005c_1_apb >> } >> link_list_1 { >> qcom-curr-link-list = 5 >> qcom-link-list = R_0x1784005c_1_apb >> } >> } >> >> The "qcom-link-list" field can have 1000s of register , based on that >> max nodes is increased to 8192. > > OK, then the number of fields can be larger than 1000. I got it. > >> >>> >>>> Can you let us know the changes that you suggest for doing the same? Is >>>> it fine to just increase the XBC_NODE_MAX, do we also need to >>>> change the uint16_t to u32 for proper storing of index values? >>> >>> Expanding the number of max nodes is easy, just increase the XBC_NODE_MAX >>> (must be less than 64k). That will also increase the memory consumption >>> during the boot time even if the bootconfig is small. Anyway, it will be >>> freed after boot, so it maybe OK. >> >> So since the limit is 64K, 8192 is a valid value for max nodes. > > Yes. Expanding the number of node is OK to me. > >> >>> >>> But expanding the size of max bootconfig needs to change the type of >>> the 'data' field to uint32_t (since that will be used for building >>> bootconfig tool) and you also must confirm that `tools/bootconfig/bootconfig` >>> can be built and pass the test-bootconfig.sh. >>> Hmm, comparing with expanding the max number of XBC node, changing the >>> 'data' type to uint32_t may not have much impact on memory consumption point >>> of view, because it may increase only 20% of memory, but expanding the >>> MAX_XBC_NODE always increases more than double. >>> >>> Thus, if we can accept increasing the number of node, it should be OK to >>> change the 'data' type. >> >> That means from DCC point of view only increasing the max nodes is >> enough as increasing the data size is unrelated to increasing the max nodes? > > Yes, if it is less than 32KB, you just need to increase the XBC_NODE_MAX. > But if you think the size of bootconfig, we have to change the type of > xbc_node::data field. > > Can you check the DCC also need to expand the size of bootconfig limitation? > > Thank you!
Yes, I don't think the index needs to be increased from u16 to u32 for dcc. Will be sending out the next version accordingly.
Thanks > >> >>> >>> BTW, I think now we don't need the ' __attribute__ ((__packed__))' for >>> struct xbc_node. It was packed for reducing the size of array and able to >>> pass 'compiled' bootconfig, but now it is just passed as a text data for >>> safety. >> >>> >>> Thank you, >>> >>>> >>>> >>>>> >>>>>> >>>>>> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@quicinc.com> >>>>>> --- >>>>>> include/linux/bootconfig.h | 6 +++--- >>>>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>>>> >>>>>> diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h >>>>>> index 1611f9d..64d233b 100644 >>>>>> --- a/include/linux/bootconfig.h >>>>>> +++ b/include/linux/bootconfig.h >>>>>> @@ -55,11 +55,11 @@ struct xbc_node { >>>>>> } __attribute__ ((__packed__)); >>>>>> >>>>>> #define XBC_KEY 0 >>>>>> -#define XBC_VALUE (1 << 15) >>>>>> -/* Maximum size of boot config is 32KB - 1 */ >>>>>> +#define XBC_VALUE (1 << 18) >>>>>> +/* Maximum size of boot config is 256KB - 1 */ >>>>>> #define XBC_DATA_MAX (XBC_VALUE - 1) >>>>>> >>>>>> -#define XBC_NODE_MAX 1024 >>>>>> +#define XBC_NODE_MAX 8192 >>>>>> #define XBC_KEYLEN_MAX 256 >>>>>> #define XBC_DEPTH_MAX 16 >>>>>> >>>>>> -- >>>>>> 2.7.4 >>>>>> >>>>> >>>>> >>> >>> > >
| ![\](/images/icornerr.gif) |