Re: [RFC PATCH v4 2/4] Adding basic custom/vendor CSR handling mechanism

["Ruinland Chuan-Tzu Tsa(蔡傳資)" <ruinland@andestech.com>]

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Hi Bin and Alistair,


>> +#if defined(CONFIG_RISCV_CUSTOM)
>> +static void setup_custom_csr(CPURISCVState *env,
>> +                             riscv_custom_csr_operations csr_map_struct[]
>> +                             ) {

>{ should be put to the next line, per QEMU coding convention. Please
>fix this globally in this series.

Will do

>> +
>> +    env->custom_csr_map = g_hash_table_new_full(g_direct_hash, \
>> +                                                g_direct_equal, \
>> +                                                NULL, NULL);

> Is it possible to juse use g_hash_table_new() directly, with both 2
> parameters being NULL, given you don't provide the destroy hooks?
> like:
>
>    env->custom_csr_map = g_hash_table_new(NULL, NULL);

I can try.

>> +
>> +
>> +    int i;

>nits: please move this to the beginning of this function.

Will do.

>> +    for (i = 0; i < MAX_CUSTOM_CSR_NUM; i++) {
>> +        if (csr_map_struct[i].csrno != 0) {
>> +            g_hash_table_insert(env->custom_csr_map,
>> +                GINT_TO_POINTER(csr_map_struct[i].csrno),
>> +                &csr_map_struct[i].csr_opset);
>> +        } else {
>> +            break;

>break? I think we should continue the loop.

Please refer to Patch 4.
The table is null-ended.
Thus it's a break here.


>> +typedef struct {
>> +    int csrno;
>> +    riscv_csr_operations csr_opset;
>> +    } riscv_custom_csr_operations;

> } should be put in the beginning without space. Please fix this
> globally in this series.

Will do.

> +
> +/*
> + * The reason why we have an abstraction here is that : We could have CSR
> + * number M on hart A is an alias of CSR number N on hart B. So we make a
> + * CSR number to value address map.
> + */
> +typedef struct  {
> +    int csrno;
> +    target_ulong val;
> +    } riscv_custom_csr_vals;
> +

It looks this struct is not used by any patch in this series?

>>  /* CSR function table constants */
>>  enum {
>> -    CSR_TABLE_SIZE = 0x1000
>> +    CSR_TABLE_SIZE = 0x1000,
>> +    MAX_CUSTOM_CSR_NUM = 100

>To be consistent, name this to be: CUSTOM_CSR_TABLE_SIZE

Sounds reasonable.

>>  /* CSR function table */
>> +extern int andes_custom_csr_size;
>> +extern riscv_custom_csr_operations andes_custom_csr_table[MAX_CUSTOM_CSR_NUM];

>The above 2 should not be in this patch.
Could you elaborate a little bit more ?

>>  extern riscv_csr_operations csr_ops[CSR_TABLE_SIZE];
>>
>>  void riscv_get_csr_ops(int csrno, riscv_csr_operations *ops);
>>  void riscv_set_csr_ops(int csrno, riscv_csr_operations *ops);
>>
>> +

>This is unnecessary.
Sorry for the newline.

>> -#if !defined(CONFIG_USER_ONLY)
>> +#pragma GCC diagnostic push
>> +#pragma GCC diagnostic ignored "-Wunused-function"

>Use __attribute__((__unused__)), so we don't need to use GCC push/pop
Thanks for the tips.
Will do.

>> +/*
>> + * XXX: This is just a write stub for developing custom CSR handler,

>Remove XXX
Will do.

>> + * if the behavior of writting such CSR is not presentable in QEMU and doesn't

>typo: writing.

>Is that present, or presentable?

It's not a writing typo. I mean "presentable" with its literal meaning.
If we cannot demonstrate a hardware feature inside QEMU, we can just stub it.


>> +#if defined(CONFIG_RISCV_CUSTOM)
>> +/* Custom CSR related routines and data structures */
>> +
>> +static gpointer is_custom_csr(CPURISCVState *env, int csrno)

>The function name suggests that the return value should be of bool
>type. Suggest we do:

>static bool is_custom_csr(CPURISCVState *env, int csrno,
>riscv_custom_csr_operations *custom_csr_ops)

Thanks for the advice, will modify it for V5.


>> +
>> +

>Unnecessary changes
Sorry for the newline.

>>  int riscv_csrrw(CPURISCVState *env, int csrno, target_ulong *ret_value,
>>                  target_ulong new_value, target_ulong write_mask)
>>  {
>>      int ret;
>>      target_ulong old_value;
>>      RISCVCPU *cpu = env_archcpu(env);
>> +    #if !defined(CONFIG_RISCV_CUSTOM)

>Please make sure #if starts from the beginning of this line, without space ahead
Will do.

>> +    riscv_csr_operations *csrop = &csr_ops[csrno];

>nits: name this variable to csr_ops

It will collide with original csr_ops.
I'll change to another name.


>>
>> +#if defined(CONFIG_RISCV_CUSTOM)
>> +/* Include the custom CSR table here. */

>nits: remove the ending .
Will do.
Sorry for all these style format issues.
I must I cherry-picked a wrong before I ran checkpatch.pl.

>> +/* This file is intentionally left blank at this commit. */

>nits: remove the ending .

>%s/at/in

Will do.

>Regards,
>Bin

Thanks for the quick reply and advice.
I'll cook the v5 ASAP.

Best regards,
Ruinland
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